summaryrefslogtreecommitdiff
path: root/src/engine/SCons/Environment.xml
blob: 85ba340ecd940eae7e7bea65073a1256c4d225aa (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
<!--
Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 The SCons Foundation

This file is processed by the bin/SConsDoc.py module.
See its __doc__ string for a discussion of the format.
-->

<!-- Construction variables -->

<cvar name="BUILDERS">
<summary>
A dictionary mapping the names of the builders
available through this environment
to underlying Builder objects.
Builders named
Alias, CFile, CXXFile, DVI, Library, Object, PDF, PostScript, and Program
are available by default.
If you initialize this variable when an
Environment is created:

<example>
env = Environment(BUILDERS = {'NewBuilder' : foo})
</example>

the default Builders will no longer be available.
To use a new Builder object in addition to the default Builders,
add your new Builder object like this:

<example>
env = Environment()
env.Append(BUILDERS = {'NewBuilder' : foo})
</example>

or this:

<example>
env = Environment()
env['BUILDERS]['NewBuilder'] = foo
</example>
</summary>
</cvar>

<cvar name="Dir">
<summary>
A function that converts a string
into a Dir instance relative to the target being built.
</summary>
</cvar>

<cvar name="ENV">
<summary>
A dictionary of environment variables
to use when invoking commands. When
&cv-ENV; is used in a command all list
values will be joined using the path separator and any other non-string
values will simply be coerced to a string.
Note that, by default,
&scons;
does
<emphasis>not</emphasis>
propagate the environment in force when you
execute
&scons;
to the commands used to build target files.
This is so that builds will be guaranteed
repeatable regardless of the environment
variables set at the time
&scons;
is invoked.

If you want to propagate your
environment variables
to the commands executed
to build target files,
you must do so explicitly:

<example>
import os
env = Environment(ENV = os.environ)
</example>

Note that you can choose only to propagate
certain environment variables.
A common example is
the system
<envar>PATH</envar>
environment variable,
so that
&scons;
uses the same utilities
as the invoking shell (or other process):

<example>
import os
env = Environment(ENV = {'PATH' : os.environ['PATH']})
</example>
</summary>
</cvar>

<cvar name="File">
<summary>
A function that converts a string into a File instance relative to the
target being built.
</summary>
</cvar>

<cvar name="SCANNERS">
<summary>
A list of the available implicit dependency scanners.
New file scanners may be added by
appending to this list,
although the more flexible approach
is to associate scanners
with a specific Builder.
See the sections "Builder Objects"
and "Scanner Objects,"
below, for more information.
</summary>
</cvar>

<cvar name="CHANGED_SOURCES">
<summary>
A reserved variable name
that may not be set or used in a construction environment.
(See "Variable Substitution," below.)
</summary>
</cvar>

<cvar name="CHANGED_TARGETS">
<summary>
A reserved variable name
that may not be set or used in a construction environment.
(See "Variable Substitution," below.)
</summary>
</cvar>

<cvar name="SOURCE">
<summary>
A reserved variable name
that may not be set or used in a construction environment.
(See "Variable Substitution," below.)
</summary>
</cvar>

<cvar name="SOURCES">
<summary>
A reserved variable name
that may not be set or used in a construction environment.
(See "Variable Substitution," below.)
</summary>
</cvar>

<cvar name="TARGET">
<summary>
A reserved variable name
that may not be set or used in a construction environment.
(See "Variable Substitution," below.)
</summary>
</cvar>

<cvar name="TARGETS">
<summary>
A reserved variable name
that may not be set or used in a construction environment.
(See "Variable Substitution," below.)
</summary>
</cvar>

<cvar name="UNCHANGED_SOURCES">
<summary>
A reserved variable name
that may not be set or used in a construction environment.
(See "Variable Substitution," below.)
</summary>
</cvar>

<cvar name="UNCHANGED_TARGETS">
<summary>
A reserved variable name
that may not be set or used in a construction environment.
(See "Variable Substitution," below.)
</summary>
</cvar>

<cvar name="TOOLS">
<summary>
A list of the names of the Tool specifications
that are part of this construction environment.
</summary>
</cvar>

<!-- Functions /  Construction environment methods -->

<scons_function name="Action">
<arguments>
(action, [cmd/str/fun, [var, ...]] [option=value, ...])
</arguments>
<summary>
Creates an Action object for
the specified
<varname>action</varname>.
See the section "Action Objects,"
below, for a complete explanation of the arguments and behavior.

Note that the
<function>env.Action</function>()
form of the invocation will expand
construction variables in any argument strings,
including the
<varname>action</varname>
argument, at the time it is called
using the construction variables in the
<varname>env</varname>
construction environment through which
<function>env.Action</function>()
was called.
The
<function>Action</function>()
form delays all variable expansion
until the Action object is actually used.
</summary>
</scons_function>

<scons_function name="AddMethod">
<arguments signature="global">
(object, function, [name])
</arguments>
<arguments signature="env">
(function, [name])
</arguments>
<summary>
When called with the
<function>AddMethod</function>()
form,
adds the specified
<varname>function</varname>
to the specified
<varname>object</varname>
as the specified method
<varname>name</varname>.
When called with the
<function>env.AddMethod</function>()
form,
adds the specified
<varname>function</varname>
to the construction environment
<varname>env</varname>
as the specified method
<varname>name</varname>.
In both cases, if
<varname>name</varname>
is omitted or
<literal>None</literal>,
the name of the
specified
<varname>function</varname>
itself is used for the method name.

Examples:

<example>
# Note that the first argument to the function to
# be attached as a method must be the object through
# which the method will be called; the Python
# convention is to call it 'self'.
def my_method(self, arg):
    print "my_method() got", arg

# Use the global AddMethod() function to add a method
# to the Environment class.  This
AddMethod(Environment, my_method)
env = Environment()
env.my_method('arg')

# Add the function as a method, using the function
# name for the method call.
env = Environment()
env.AddMethod(my_method, 'other_method_name')
env.other_method_name('another arg')
</example>
</summary>
</scons_function>

<scons_function name="AddPostAction">
<arguments>
(target, action)
</arguments>
<summary>
Arranges for the specified
<varname>action</varname>
to be performed
after the specified
<varname>target</varname>
has been built.
The specified action(s) may be
an Action object, or anything that
can be converted into an Action object
(see below).

When multiple targets are supplied,
the action may be called multiple times,
once after each action that generates
one or more targets in the list.
</summary>
</scons_function>

<scons_function name="AddPreAction">
<arguments>
(target, action)
</arguments>
<summary>
Arranges for the specified
<varname>action</varname>
to be performed
before the specified
<varname>target</varname>
is built.
The specified action(s) may be
an Action object, or anything that
can be converted into an Action object
(see below).

When multiple targets are specified,
the action(s) may be called multiple times,
once before each action that generates
one or more targets in the list.

Note that if any of the targets are built in multiple steps,
the action will be invoked just
before the "final" action that specifically
generates the specified target(s).
For example, when building an executable program
from a specified source
<filename>.c</filename>
file via an intermediate object file:

<example>
foo = Program('foo.c')
AddPreAction(foo, 'pre_action')
</example>

The specified
<literal>pre_action</literal>
would be executed before
&scons;
calls the link command that actually
generates the executable program binary
<filename>foo</filename>,
not before compiling the
<filename>foo.c</filename>
file into an object file.
</summary>
</scons_function>

<scons_function name="Alias">
<arguments>
(alias, [targets, [action]])
</arguments>
<summary>
Creates one or more phony targets that
expand to one or more other targets.
An optional
<varname>action</varname>
(command)
or list of actions
can be specified that will be executed
whenever the any of the alias targets are out-of-date.
Returns the Node object representing the alias,
which exists outside of any file system.
This Node object, or the alias name,
may be used as a dependency of any other target,
including another alias.
&f-Alias;
can be called multiple times for the same
alias to add additional targets to the alias,
or additional actions to the list for this alias.

Examples:

<example>
Alias('install')
Alias('install', '/usr/bin')
Alias(['install', 'install-lib'], '/usr/local/lib')

env.Alias('install', ['/usr/local/bin', '/usr/local/lib'])
env.Alias('install', ['/usr/local/man'])

env.Alias('update', ['file1', 'file2'], "update_database $SOURCES")
</example>
</summary>
</scons_function>

<scons_function name="AlwaysBuild">
<arguments>
(target, ...)
</arguments>
<summary>
Marks each given
<varname>target</varname>
so that it is always assumed to be out of date,
and will always be rebuilt if needed.
Note, however, that
&f-AlwaysBuild;
does not add its target(s) to the default target list,
so the targets will only be built
if they are specified on the command line,
or are a dependent of a target specified on the command line--but
they will
<emphasis>always</emphasis>
be built if so specified.
Multiple targets can be passed in to a single call to
&f-AlwaysBuild;.
</summary>
</scons_function>

<scons_function name="Append">
<arguments signature="env">
(key=val, [...])
</arguments>
<summary>
Appends the specified keyword arguments
to the end of construction variables in the environment.
If the Environment does not have
the specified construction variable,
it is simply added to the environment.
If the values of the construction variable
and the keyword argument are the same type,
then the two values will be simply added together.
Otherwise, the construction variable
and the value of the keyword argument
are both coerced to lists,
and the lists are added together.
(See also the Prepend method, below.)

Example:

<example>
env.Append(CCFLAGS = ' -g', FOO = ['foo.yyy'])
</example>
</summary>
</scons_function>

<scons_function name="AppendENVPath">
<arguments signature="env">
(name, newpath, [envname, sep, delete_existing])
</arguments>
<summary>
This appends new path elements to the given path in the
specified external environment
(<literal>ENV</literal>
by default).
This will only add
any particular path once (leaving the last one it encounters and
ignoring the rest, to preserve path order),
and to help assure this,
will normalize all paths (using
<function>os.path.normpath</function>
and
<function>os.path.normcase</function>).
This can also handle the
case where the given old path variable is a list instead of a
string, in which case a list will be returned instead of a string.

If 
<varname>delete_existing</varname>
is 0, then adding a path that already exists
will not move it to the end; it will stay where it is in the list.

Example:

<example>
print 'before:',env['ENV']['INCLUDE']
include_path = '/foo/bar:/foo'
env.AppendENVPath('INCLUDE', include_path)
print 'after:',env['ENV']['INCLUDE']

yields:
before: /foo:/biz
after: /biz:/foo/bar:/foo
</example>
</summary>
</scons_function>

<scons_function name="AppendUnique">
<arguments signature="env">
(key=val, [...], delete_existing=0)
</arguments>
<summary>
Appends the specified keyword arguments
to the end of construction variables in the environment.
If the Environment does not have
the specified construction variable,
it is simply added to the environment.
If the construction variable being appended to is a list,
then any value(s) that already exist in the
construction variable will
<emphasis>not</emphasis>
be added again to the list.
However, if delete_existing is 1, 
existing matching values are removed first, so
existing values in the arg list move to the end of the list.

Example:

<example>
env.AppendUnique(CCFLAGS = '-g', FOO = ['foo.yyy'])
</example>
</summary>
</scons_function>

<scons_function name="BuildDir">
<arguments>
(build_dir, src_dir, [duplicate])
</arguments>
<summary>
Deprecated synonyms for
&f-VariantDir;
and
<function>env.VariantDir</function>().
The
<varname>build_dir</varname>
argument becomes the
<varname>variant_dir</varname>
argument of
&f-VariantDir;
or
<function>env.VariantDir</function>().
</summary>
</scons_function>

<scons_function name="Builder">
<arguments>
(action, [arguments])
</arguments>
<summary>
Creates a Builder object for
the specified
<varname>action</varname>.
See the section "Builder Objects,"
below, for a complete explanation of the arguments and behavior.

Note that the
<function>env.Builder</function>()
form of the invocation will expand
construction variables in any arguments strings,
including the
<varname>action</varname>
argument,
at the time it is called
using the construction variables in the
<varname>env</varname>
construction environment through which
<function>env.Builder</function>()
was called.
The
&f-Builder;
form delays all variable expansion
until after the Builder object is actually called.
</summary>
</scons_function>

<scons_function name="CacheDir">
<arguments>
(cache_dir)
</arguments>
<summary>
Specifies that
&scons;
will maintain a cache of derived files in
<varname>cache_dir</varname>.
The derived files in the cache will be shared
among all the builds using the same
&f-CacheDir;
call.
Specifying a
<varname>cache_dir</varname>
of
<literal>None</literal>
disables derived file caching.

Calling
<function>env.CacheDir</function>()
will only affect targets built
through the specified construction environment.
Calling
&f-CacheDir;
sets a global default
that will be used by all targets built
through construction environments
that do
<emphasis>not</emphasis>
have an
<function>env.CacheDir</function>()
specified.

When a
<function>CacheDir</function>()
is being used and
&scons;
finds a derived file that needs to be rebuilt,
it will first look in the cache to see if a
derived file has already been built
from identical input files and an identical build action
(as incorporated into the MD5 build signature).
If so,
&scons;
will retrieve the file from the cache.
If the derived file is not present in the cache,
&scons;
will rebuild it and
then place a copy of the built file in the cache
(identified by its MD5 build signature),
so that it may be retrieved by other
builds that need to build the same derived file
from identical inputs.

Use of a specified
&f-CacheDir;
may be disabled for any invocation
by using the
<option>--cache-disable</option>
option.

If the
<option>--cache-force</option>
option is used,
&scons;
will place a copy of
<emphasis>all</emphasis>
derived files in the cache,
even if they already existed
and were not built by this invocation.
This is useful to populate a cache
the first time
&f-CacheDir;
is added to a build,
or after using the
<option>--cache-disable</option>
option.

When using
&f-CacheDir;,
&scons;
will report,
"Retrieved `file' from cache,"
unless the
<option>--cache-show</option>
option is being used.
When the
<option>--cache-show</option>
option is used,
&scons;
will print the action that
<emphasis>would</emphasis>
have been used to build the file,
without any indication that
the file was actually retrieved from the cache.
This is useful to generate build logs
that are equivalent regardless of whether
a given derived file has been built in-place
or retrieved from the cache.

The
&f-link-NoCache;
method can be used to disable caching of specific files.  This can be
useful if inputs and/or outputs of some tool are impossible to
predict or prohibitively large.
</summary>
</scons_function>

<scons_function name="Clean">
<arguments>
(targets, files_or_dirs)
</arguments>
<summary>
This specifies a list of files or directories which should be removed
whenever the targets are specified with the
<option>-c</option>
command line option.
The specified targets may be a list
or an individual target.
Multiple calls to
&f-Clean;
are legal,
and create new targets or add files and directories to the
clean list for the specified targets.

Multiple files or directories should be specified
either as separate arguments to the
&f-Clean;
method, or as a list.
&f-Clean;
will also accept the return value of any of the construction environment
Builder methods.
Examples:

The related
&f-link-NoClean;
function overrides calling
&f-Clean;
for the same target,
and any targets passed to both functions will
<emphasis>not</emphasis>
be removed by the
<option>-c</option>
option.

Examples:

<example>
Clean('foo', ['bar', 'baz'])
Clean('dist', env.Program('hello', 'hello.c'))
Clean(['foo', 'bar'], 'something_else_to_clean')
</example>

In this example,
installing the project creates a subdirectory for the documentation.
This statement causes the subdirectory to be removed
if the project is deinstalled.
<example>
Clean(docdir, os.path.join(docdir, projectname))
</example>
</summary>
</scons_function>

<scons_function name="Clone">
<arguments signature="env">
([key=val, ...])
</arguments>
<summary>
Returns a separate copy of a construction environment.
If there are any keyword arguments specified,
they are added to the returned copy,
overwriting any existing values
for the keywords.

Example:

<example>
env2 = env.Clone()
env3 = env.Clone(CCFLAGS = '-g')
</example>

Additionally, a list of tools and a toolpath may be specified, as in
the Environment constructor:

<example>
def MyTool(env): env['FOO'] = 'bar'
env4 = env.Clone(tools = ['msvc', MyTool])
</example>

The
<varname>parse_flags</varname>
keyword argument is also recognized:

<example>
# create an environment for compiling programs that use wxWidgets
wx_env = env.Clone(parse_flags = '!wx-config --cflags --cxxflags')
</example>
</summary>
</scons_function>

<builder name="Command">
<summary>
The &b-Command; "Builder" is actually implemented
as a function that looks like a Builder,
but actually takes an additional argument of the action
from which the Builder should be made.
See the &f-link-Command; function description
for the calling syntax and details.
</summary>
</builder>

<scons_function name="Command">
<arguments>
(target, source, action, [key=val, ...])
</arguments>
<summary>
Executes a specific action
(or list of actions)
to build a target file or files.
This is more convenient
than defining a separate Builder object
for a single special-case build.

As a special case, the
<varname>source_scanner</varname>
keyword argument can
be used to specify
a Scanner object
that will be used to scan the sources.
(The global
<literal>DirScanner</literal>
object can be used
if any of the sources will be directories
that must be scanned on-disk for
changes to files that aren't
already specified in other Builder of function calls.)

Any other keyword arguments specified override any
same-named existing construction variables.

An action can be an external command,
specified as a string,
or a callable Python object;
see "Action Objects," below,
for more complete information.
Also note that a string specifying an external command
may be preceded by an
<literal>@</literal>
(at-sign)
to suppress printing the command in question,
or by a
<literal>-</literal>
(hyphen)
to ignore the exit status of the external command.

Examples:

<example>
env.Command('foo.out', 'foo.in',
            "$FOO_BUILD &lt; $SOURCES &gt; $TARGET")

env.Command('bar.out', 'bar.in',
            ["rm -f $TARGET",
             "$BAR_BUILD &lt; $SOURCES &gt; $TARGET"],
            ENV = {'PATH' : '/usr/local/bin/'})

def rename(env, target, source):
    import os
    os.rename('.tmp', str(target[0]))

env.Command('baz.out', 'baz.in',
            ["$BAZ_BUILD &lt; $SOURCES &gt; .tmp",
	     rename ])
</example>

Note that the
&f-Command;
function will usually assume, by default,
that the specified targets and/or sources are Files,
if no other part of the configuration
identifies what type of entry it is.
If necessary, you can explicitly specify
that targets or source nodes should
be treated as directoriese
by using the
&f-link-Dir;
or
<function>env.Dir</function>()
functions.

Examples:

<example>
env.Command('ddd.list', Dir('ddd'), 'ls -l $SOURCE > $TARGET')

env['DISTDIR'] = 'destination/directory'
env.Command(env.Dir('$DISTDIR')), None, make_distdir)
</example>

(Also note that SCons will usually
automatically create any directory necessary to hold a target file,
so you normally don't need to create directories by hand.)
</summary>
</scons_function>

<scons_function name="Configure">
<arguments signature="global">
(env, [custom_tests, conf_dir, log_file, config_h])
</arguments>
<arguments signature="env">
([custom_tests, conf_dir, log_file, config_h])
</arguments>
<summary>
Creates a Configure object for integrated
functionality similar to GNU autoconf.
See the section "Configure Contexts,"
below, for a complete explanation of the arguments and behavior.
</summary>
</scons_function>

<scons_function name="Copy">
<arguments signature="env">
([key=val, ...])
</arguments>
<summary>
A now-deprecated synonym for
<function>env.Clone</function>().
</summary>
</scons_function>

<scons_function name="Decider">
<arguments>
(function)
</arguments>
<summary>
Specifies that all up-to-date decisions for
targets built through this construction environment
will be handled by the specified
<varname>function</varname>.
The
<varname>function</varname>
can be one of the following strings
that specify the type of decision function
to be performed:

<variablelist>
<varlistentry>
<term><literal>timestamp-newer</literal></term>
<listitem>
<para>
Specifies that a target shall be considered out of date and rebuilt
if the dependency's timestamp is newer than the target file's timestamp.
This is the behavior of the classic Make utility,
and
<literal>make</literal>
can be used a synonym for
<literal>timestamp-newer</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>timestamp-match</literal></term>
<listitem>
<para>
Specifies that a target shall be considered out of date and rebuilt
if the dependency's timestamp is different than the
timestamp recorded the last time the target was built.
This provides behavior very similar to the classic Make utility
(in particular, files are not opened up so that their
contents can be checksummed)
except that the target will also be rebuilt if a
dependency file has been restored to a version with an
<emphasis>earlier</emphasis>
timestamp, such as can happen when restoring files from backup archives.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>MD5</literal></term>
<listitem>
<para>
Specifies that a target shall be considered out of date and rebuilt
if the dependency's content has changed sine the last time
the target was built,
as determined be performing an MD5 checksum
on the dependency's contents
and comparing it to the checksum recorded the
last time the target was built.
<literal>content</literal>
can be used as a synonym for
<literal>MD5</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>MD5-timestamp</literal></term>
<listitem>
<para>
Specifies that a target shall be considered out of date and rebuilt
if the dependency's content has changed sine the last time
the target was built,
except that dependencies with a timestamp that matches
the last time the target was rebuilt will be
assumed to be up-to-date and
<emphasis>not</emphasis>
rebuilt.
This provides behavior very similar
to the
<literal>MD5</literal>
behavior of always checksumming file contents,
with an optimization of not checking
the contents of files whose timestamps haven't changed.
The drawback is that SCons will
<emphasis>not</emphasis>
detect if a file's content has changed
but its timestamp is the same,
as might happen in an automated script
that runs a build,
updates a file,
and runs the build again,
all within a single second.
</para>
</listitem>
</varlistentry>
</variablelist>

Examples:

<example>
# Use exact timestamp matches by default.
Decider('timestamp-match')

# Use MD5 content signatures for any targets built
# with the attached construction environment.
env.Decider('content')
</example>

In addition to the above already-available functions,
the
<varname>function</varname>
argument may be an actual Python function
that takes the following three arguments:

<variablelist>
<varlistentry>
<term><parameter>dependency</parameter></term>
<listitem>
<para>
The Node (file) which
should cause the
<varname>target</varname>
to be rebuilt
if it has "changed" since the last tme
<varname>target</varname>
was built.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>target</parameter></term>
<listitem>
<para>
The Node (file) being built.
In the normal case,
this is what should get rebuilt
if the
<varname>dependency</varname>
has "changed."
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>prev_ni</parameter></term>
<listitem>
<para>
Stored information about the state of the
<varname>dependency</varname>
the last time the
<varname>target</varname>
was built.
This can be consulted to match various
file characteristics
such as the timestamp,
size, or content signature.
</para>
</listitem>
</varlistentry>
</variablelist>

The
<varname>function</varname>
should return a
<literal>True</literal>
(non-zero)
value if the
<varname>dependency</varname>
has "changed" since the last time
the
<varname>target</varname>
was built
(indicating that the target
<emphasis>should</emphasis>
be rebuilt),
and
<literal>False</literal>
(zero)
otherwise
(indicating that the target should
<emphasis>not</emphasis>
be rebuilt).
Note that the decision can be made
using whatever criteria are appopriate.
Ignoring some or all of the function arguments
is perfectly normal.

Example:

<example>
def my_decider(dependency, target, prev_ni):
    return not os.path.exists(str(target))

env.Decider(my_decider)
</example>
</summary>
</scons_function>

<scons_function name="Depends">
<arguments>
(target, dependency)
</arguments>
<summary>
Specifies an explicit dependency;
the
<varname>target</varname>
will be rebuilt
whenever the
<varname>dependency</varname>
has changed.
Both the specified
<varname>target</varname>
and
<varname>dependency</varname>
can be a string
(usually the path name of a file or directory)
or Node objects,
or a list of strings or Node objects
(such as returned by a Builder call).
This should only be necessary
for cases where the dependency
is not caught by a Scanner
for the file.

Example:

<example>
env.Depends('foo', 'other-input-file-for-foo')

mylib = env.Library('mylib.c')
installed_lib = env.Install('lib', mylib)
bar = env.Program('bar.c')

# Arrange for the library to be copied into the installation
# directory before trying to build the "bar" program.
# (Note that this is for example only.  A "real" library
# dependency would normally be configured through the $LIBS
# and $LIBPATH variables, not using an env.Depends() call.)

env.Depends(bar, installed_lib)
</example>
</summary>
</scons_function>

<scons_function name="Dictionary">
<arguments signature="env">
([vars])
</arguments>
<summary>
Returns a dictionary object
containing copies of all of the
construction variables in the environment.
If there are any variable names specified,
only the specified construction
variables are returned in the dictionary.

Example:

<example>
dict = env.Dictionary()
cc_dict = env.Dictionary('CC', 'CCFLAGS', 'CCCOM')
</example>
</summary>
</scons_function>

<scons_function name="Dir">
<arguments>
(name, [directory])
</arguments>
<summary>
This returns a Directory Node,
an object that represents the specified directory
<varname>name</varname>.
<varname>name</varname>
can be a relative or absolute path.
<varname>directory</varname>
is an optional directory that will be used as the parent directory.
If no
<varname>directory</varname>
is specified, the current script's directory is used as the parent.

If
<varname>name</varname>
is a list, SCons returns a list of Dir nodes.
Construction variables are expanded in
<varname>name</varname>.

Directory Nodes can be used anywhere you
would supply a string as a directory name
to a Builder method or function.
Directory Nodes have attributes and methods
that are useful in many situations;
see "File and Directory Nodes," below.
</summary>
</scons_function>

<scons_function name="Dump">
<arguments signature="env">
([key])
</arguments>
<summary>
Returns a pretty printable representation of the environment.
<varname>key</varname>,
if not
<literal>None</literal>,
should be a string containing the name of the variable of interest.

This SConstruct:

<example>
env=Environment()
print env.Dump('CCCOM')
</example>

will print:

<example>
'$CC -c -o $TARGET $CCFLAGS $CPPFLAGS $_CPPDEFFLAGS $_CPPINCFLAGS $SOURCES'
</example>

While this SConstruct:

<example>
env=Environment()
print env.Dump()
</example>

will print:
<example>
{ 'AR': 'ar',
  'ARCOM': '$AR $ARFLAGS $TARGET $SOURCES\n$RANLIB $RANLIBFLAGS $TARGET',
  'ARFLAGS': ['r'],
  'AS': 'as',
  'ASCOM': '$AS $ASFLAGS -o $TARGET $SOURCES',
  'ASFLAGS': [],
  ...
</example>
</summary>
</scons_function>

<scons_function name="Environment">
<arguments>
([key=value, ...])
</arguments>
<summary>
Return a new construction environment
initialized with the specified
<varname>key</varname><literal>=</literal><varname>value</varname>
pairs.
</summary>
</scons_function>

<scons_function name="Execute">
<arguments>
(action, [strfunction, varlist])
</arguments>
<summary>
Executes an Action object.
The specified
<varname>action</varname>
may be an Action object
(see the section "Action Objects,"
below, for a complete explanation of the arguments and behavior),
or it may be a command-line string,
list of commands,
or executable Python function,
each of which will be converted
into an Action object
and then executed.
The exit value of the command
or return value of the Python function
will be returned.

Note that
&scons;
will print an error message if the executed
<varname>action</varname>
fails--that is,
exits with or returns a non-zero value.
&scons;
will
<emphasis>not</emphasis>,
however,
automatically terminate the build
if the specified
<varname>action</varname>
fails.
If you want the build to stop in response to a failed
&f-Execute;
call,
you must explicitly check for a non-zero return value:

<example>
Execute(Copy('file.out', 'file.in'))

if Execute("mkdir sub/dir/ectory"):
    # The mkdir failed, don't try to build.
    Exit(1)
</example>
</summary>
</scons_function>

<scons_function name="File">
<arguments>
(name, [directory])
</arguments>
<summary>
This returns a
File Node,
an object that represents the specified file
<varname>name</varname>.
<varname>name</varname>
can be a relative or absolute path.
<varname>directory</varname>
is an optional directory that will be used as the parent directory.

If
<varname>name</varname>
is a list, SCons returns a list of File nodes.
Construction variables are expanded in
<varname>name</varname>.

File Nodes can be used anywhere you
would supply a string as a file name
to a Builder method or function.
File Nodes have attributes and methods
that are useful in many situations;
see "File and Directory Nodes," below.
</summary>
</scons_function>

<scons_function name="FindFile">
<arguments>
(file, dirs)
</arguments>
<summary>
Search for
<varname>file</varname>
in the path specified by
<varname>dirs</varname>.
<varname>dirs</varname>
may be a list of directory names or a single directory name.
In addition to searching for files that exist in the filesystem,
this function also searches for derived files
that have not yet been built.

Example:

<example>
foo = env.FindFile('foo', ['dir1', 'dir2'])
</example>
</summary>
</scons_function>

<scons_function name="FindInstalledFiles">
<arguments>
()
</arguments>
<summary>
Returns the list of targets set up by the
&b-link-Install;
or
&b-link-InstallAs;
builders.

This function serves as a convenient method to select the contents of
a binary package.

Example:

<example>
Install( '/bin', [ 'executable_a', 'executable_b' ] )

# will return the file node list
# [ '/bin/executable_a', '/bin/executable_b' ]
FindInstalledFiles()

Install( '/lib', [ 'some_library' ] )

# will return the file node list
# [ '/bin/executable_a', '/bin/executable_b', '/lib/some_library' ]
FindInstalledFiles()
</example>
</summary>
</scons_function>

<scons_function name="FindSourceFiles">
<arguments>
(node='"."')
</arguments>
<summary>
Returns the list of nodes which serve as the source of the built files.
It does so by inspecting the dependency tree starting at the optional
argument
<varname>node</varname>
which defaults to the '"."'-node. It will then return all leaves of
<varname>node</varname>.
These are all children which have no further children.

This function is a convenient method to select the contents of a Source
Package.

Example:

<example>
Program( 'src/main_a.c' )
Program( 'src/main_b.c' )
Program( 'main_c.c' )

# returns ['main_c.c', 'src/main_a.c', 'SConstruct', 'src/main_b.c']
FindSourceFiles()

# returns ['src/main_b.c', 'src/main_a.c' ]
FindSourceFiles( 'src' )
</example>

As you can see build support files (SConstruct in the above example)
will also be returned by this function.
</summary>
</scons_function>

<scons_function name="Flatten">
<arguments>
(sequence)
</arguments>
<summary>
Takes a sequence (that is, a Python list or tuple)
that may contain nested sequences
and returns a flattened list containing
all of the individual elements in any sequence.
This can be helpful for collecting
the lists returned by calls to Builders;
other Builders will automatically
flatten lists specified as input,
but direct Python manipulation of
these lists does not.

Examples:

<example>
foo = Object('foo.c')
bar = Object('bar.c')

# Because `foo' and `bar' are lists returned by the Object() Builder,
# `objects' will be a list containing nested lists:
objects = ['f1.o', foo, 'f2.o', bar, 'f3.o']

# Passing such a list to another Builder is all right because
# the Builder will flatten the list automatically:
Program(source = objects)

# If you need to manipulate the list directly using Python, you need to
# call Flatten() yourself, or otherwise handle nested lists:
for object in Flatten(objects):
    print str(object)
</example>
</summary>
</scons_function>

<scons_function name="GetBuildPath">
<arguments>
(file, [...])
</arguments>
<summary>
Returns the
&scons;
path name (or names) for the specified
<varname>file</varname>
(or files).
The specified
<varname>file</varname>
or files
may be
&scons;
Nodes or strings representing path names.
</summary>
</scons_function>

<scons_function name="Glob">
<arguments>
(pattern, [ondisk, source, strings])
</arguments>
<summary>
Returns Nodes (or strings) that match the specified
<varname>pattern</varname>,
relative to the directory of the current
&SConscript;
file.
The
<function>env.Glob</function>()
form performs string substition on
<varname>pattern</varname>
and returns whatever matches
the resulting expanded pattern.

The specified
<varname>pattern</varname>
uses Unix shell style metacharacters for matching:

<example>
  *       matches everything
  ?       matches any single character
  [seq]   matches any character in seq
  [!seq]  matches any char not in seq
</example>

If the first character of a filename is a dot,
it must be matched explicitly.
Character matches do
<emphasis>not</emphasis>
span directory separators.

The
&f-Glob;
knows about
repositories
(see the
&f-link-Repository;
function)
and source directories
(see the
&f-link-VariantDir;
function)
and
returns a Node (or string, if so configured)
in the local (SConscript) directory
if matching Node is found
anywhere in a corresponding
repository or source directory.

The
<varname>ondisk</varname>
argument may be set to
<literal>False</literal>
(or any other non-true value)
to disable the search for matches on disk,
thereby only returning matches among
already-configured File or Dir Nodes.
The default behavior is to
return corresponding Nodes
for any on-disk matches found.

The
<varname>source</varname>
argument may be set to
<literal>True</literal>
(or any equivalent value)
to specify that,
when the local directory is a
&f-VariantDir;,
the returned Nodes should be from the
corresponding source directory,
not the local directory.

The
<varname>strings</varname>
argument may be set to
<literal>True</literal>
(or any equivalent value)
to have the
&f-Glob;
function return strings, not Nodes,
that represent the matched files or directories.
The returned strings will be relative to
the local (SConscript) directory.
(Note that This may make it easier to perform
arbitrary manipulation of file names,
but if the returned strings are
passed to a different
&SConscript;
file,
any Node translation will be relative
to the other
&SConscript;
directory,
not the original
&SConscript;
directory.)

Examples:

<example>
Program('foo', Glob('*.c'))
Zip('/tmp/everything', Glob('.??*') + Glob('*'))
</example>
</summary>
</scons_function>

<!--
<scons_function name="GlobalBuilders">
<arguments signature="global">
(flag)
</arguments>
<summary>
When
<varname>flag</varname>
is non-zero,
adds the names of the default builders
(Program, Library, etc.)
to the global name space
so they can be called without an explicit construction environment.
(This is the default.)
When
<varname>flag</varname>
is zero,
the names of the default builders are removed
from the global name space
so that an explicit construction environment is required
to call all builders.
</summary>
</scons_function>
-->

<scons_function name="Ignore">
<arguments>
(target, dependency)
</arguments>
<summary>
The specified dependency file(s)
will be ignored when deciding if
the target file(s) need to be rebuilt.

You can also use
&f-Ignore;
to remove a target from the default build.
In order to do this you must specify the directory the target will
be built in as the target, and the file you want to skip building
as the dependency.

Note that this will only remove the dependencies listed from 
the files built by default.  It will still be built if that 
dependency is needed by another object being built. 
See the third and forth examples below.

Examples:

<example>
env.Ignore('foo', 'foo.c')
env.Ignore('bar', ['bar1.h', 'bar2.h'])
env.Ignore('.','foobar.obj')
env.Ignore('bar','bar/foobar.obj')
</example>
</summary>
</scons_function>

<scons_function name="Literal">
<arguments>
(string)
</arguments>
<summary>
The specified
<varname>string</varname>
will be preserved as-is
and not have construction variables expanded.
</summary>
</scons_function>

<scons_function name="Local">
<arguments>
(targets)
</arguments>
<summary>
The specified
<varname>targets</varname>
will have copies made in the local tree,
even if an already up-to-date copy
exists in a repository.
Returns a list of the target Node or Nodes.
</summary>
</scons_function>

<!--
<scons_function name="MergeShellPaths">
<arguments signature="env">
( arg ", [" prepend ])
</arguments>
<summary>
Merges the elements of the specified
<varname>arg</varname>,
which must be a dictionary, to the construction
environment's copy of the shell environment
in env['ENV'].
(This is the environment which is passed
to subshells spawned by SCons.)
Note that
<varname>arg</varname>
must be a single value,
so multiple strings must
be passed in as a list,
not as separate arguments to
&f-MergeShellPaths;.

New values are prepended to the environment variable by default,
unless prepend=0 is specified.  
Duplicate values are always eliminated, 
since this function calls
&f-link-AppendENVPath;
or
&f-link-PrependENVPath;
depending on the
<varname>prepend</varname>
argument.  See those functions for more details.

Examples:

<example>
# Prepend a path to the shell PATH.
env.MergeShellPaths({'PATH':'/usr/local/bin'} )
# Append two dirs to the shell INCLUDE.
env.MergeShellPaths({'INCLUDE':['c:/inc1', 'c:/inc2']}, prepend=0 )
</example>
</summary>
</scons_function>
-->

<scons_function name="MergeFlags">
<arguments signature="env">
(arg, [unique])
</arguments>
<summary>
Merges the specified
<varname>arg</varname>
values to the construction environment's construction variables.
If the
<varname>arg</varname>
argument is not a dictionary,
it is converted to one by calling
&f-link-env-ParseFlags;
on the argument
before the values are merged.
Note that
<varname>arg</varname>
must be a single value,
so multiple strings must
be passed in as a list,
not as separate arguments to
&f-env-MergeFlags;.

By default,
duplicate values are eliminated;
you can, however, specify
<literal>unique=0</literal>
to allow duplicate
values to be added.
When eliminating duplicate values,
any construction variables that end with
the string
<literal>PATH</literal>
keep the left-most unique value.
All other construction variables keep
the right-most unique value.

Examples:

<example>
# Add an optimization flag to $CCFLAGS.
env.MergeFlags('-O3')

# Combine the flags returned from running pkg-config with an optimization
# flag and merge the result into the construction variables.
env.MergeFlags(['!pkg-config gtk+-2.0 --cflags', '-O3'])

# Combine an optimization flag with the flags returned from running pkg-config
# twice and merge the result into the construction variables.
env.MergeFlags(['-O3',
               '!pkg-config gtk+-2.0 --cflags --libs',
               '!pkg-config libpng12 --cflags --libs'])
</example>
</summary>
</scons_function>

<scons_function name="NoCache">
<arguments>
(target, ...)
</arguments>
<summary>
Specifies a list of files which should
<emphasis>not</emphasis>
be cached whenever the
&f-link-CacheDir;
method has been activated.
The specified targets may be a list
or an individual target.

Multiple files should be specified
either as separate arguments to the
&f-NoCache;
method, or as a list.
&f-NoCache;
will also accept the return value of any of the construction environment
Builder methods.

Calling
&f-NoCache;
on directories and other non-File Node types has no effect because
only File Nodes are cached.

Examples:

<example>
NoCache('foo.elf')
NoCache(env.Program('hello', 'hello.c'))
</example>
</summary>
</scons_function>

<scons_function name="NoClean">
<arguments>
(target, ...)
</arguments>
<summary>
Specifies a list of files or directories which should
<emphasis>not</emphasis>
be removed whenever the targets (or their dependencies)
are specified with the
<option>-c</option>
command line option.
The specified targets may be a list
or an individual target.
Multiple calls to
&f-NoClean;
are legal,
and prevent each specified target
from being removed by calls to the
<option>-c</option>
option.

Multiple files or directories should be specified
either as separate arguments to the
&f-NoClean;
method, or as a list.
&f-NoClean;
will also accept the return value of any of the construction environment
Builder methods.

Calling
&f-NoClean;
for a target overrides calling
&f-link-Clean;
for the same target,
and any targets passed to both functions will
<emphasis>not</emphasis>
be removed by the
<option>-c</option>
option.

Examples:

<example>
NoClean('foo.elf')
NoClean(env.Program('hello', 'hello.c'))
</example>
</summary>
</scons_function>

<scons_function name="ParseConfig">
<arguments signature="env">
(command, [function, unique])
</arguments>
<summary>
Calls the specified
<varname>function</varname>
to modify the environment as specified by the output of
<varname>command</varname>.
The default
<varname>function</varname>
is
&f-link-env-MergeFlags;,
which expects the output of a typical
<application>*-config</application>
command
(for example,
<application>gtk-config</application>)
and adds the options
to the appropriate construction variables.
By default,
duplicate values are not
added to any construction variables;
you can specify
<literal>unique=0</literal>
to allow duplicate
values to be added.

Interpreted options
and the construction variables they affect
are as specified for the
&f-link-env-ParseFlags;
method (which this method calls).
See that method's description, below,
for a table of options and construction variables.
</summary>
</scons_function>

<scons_function name="ParseDepends">
<arguments>
(filename, [must_exist, only_one])
</arguments>
<summary>
Parses the contents of the specified
<varname>filename</varname>
as a list of dependencies in the style of
&Make;
or
<application>mkdep</application>,
and explicitly establishes all of the listed dependencies.

By default,
it is not an error
if the specified
<varname>filename</varname>
does not exist.
The optional
<varname>must_exist</varname>
argument may be set to a non-zero
value to have
scons
throw an exception and
generate an error if the file does not exist,
or is otherwise inaccessible.

The optional
<varname>only_one</varname>
argument may be set to a non-zero
value to have
scons
thrown an exception and
generate an error
if the file contains dependency
information for more than one target.
This can provide a small sanity check
for files intended to be generated
by, for example, the
<literal>gcc -M</literal>
flag,
which should typically only
write dependency information for
one output file into a corresponding
<filename>.d</filename>
file.

The
<varname>filename</varname>
and all of the files listed therein
will be interpreted relative to
the directory of the
&SConscript;
file which calls the
&f-ParseDepends;
function.
</summary>
</scons_function>

<scons_function name="ParseFlags">
<arguments signature="env">
(flags, ...)
</arguments>
<summary>
Parses one or more strings containing
typical command-line flags for GCC tool chains
and returns a dictionary with the flag values
separated into the appropriate SCons construction variables.
This is intended as a companion to the
&f-link-env-MergeFlags;
method, but allows for the values in the returned dictionary
to be modified, if necessary,
before merging them into the construction environment.
(Note that
&f-env-MergeFlags;
will call this method if its argument is not a dictionary,
so it is usually not necessary to call
&f-link-env-ParseFlags;
directly unless you want to manipulate the values.)

If the first character in any string is
an exclamation mark (!),
the rest of the string is executed as a command,
and the output from the command is
parsed as GCC tool chain command-line flags
and added to the resulting dictionary.

Flag values are translated accordig to the prefix found,
and added to the following construction variables:

<example>
-arch               CCFLAGS, LINKFLAGS
-D                  CPPDEFINES
-framework          FRAMEWORKS
-frameworkdir=      FRAMEWORKPATH
-include            CCFLAGS
-isysroot           CCFLAGS, LINKFLAGS
-I                  CPPPATH
-l                  LIBS
-L                  LIBPATH
-mno-cygwin         CCFLAGS, LINKFLAGS
-mwindows           LINKFLAGS
-pthread            CCFLAGS, LINKFLAGS
-std=               CFLAGS
-Wa,                ASFLAGS, CCFLAGS
-Wl,-rpath=         RPATH
-Wl,-R,             RPATH
-Wl,-R              RPATH
-Wl,                LINKFLAGS
-Wp,                CPPFLAGS
-                   CCFLAGS
+                   CCFLAGS, LINKFLAGS
</example>

Any other strings not associated with options
are assumed to be the names of libraries
and added to the
&cv-LIBS;
construction variable.

Examples (all of which produce the same result):

<example>
dict = env.ParseFlags('-O2 -Dfoo -Dbar=1')
dict = env.ParseFlags('-O2', '-Dfoo', '-Dbar=1')
dict = env.ParseFlags(['-O2', '-Dfoo -Dbar=1'])
dict = env.ParseFlags('-O2', '!echo -Dfoo -Dbar=1')
</example>
</summary>
</scons_function>

<scons_function name="Platform">
<arguments signature="global">
(string)
</arguments>
<summary>
The
&f-Platform;
form returns a callable object
that can be used to initialize
a construction environment using the
platform keyword of the
&f-Environment;
function.

Example:

<example>
env = Environment(platform = Platform('win32'))
</example>

The
&f-env-Platform;
form applies the callable object for the specified platform
<varname>string</varname>
to the environment through which the method was called.

<example>
env.Platform('posix')
</example>

Note that the
<literal>win32</literal>
platform adds the
<literal>SystemDrive</literal>
and
<literal>SystemRoot</literal>
variables from the user's external environment
to the construction environment's
&cv-link-ENV;
dictionary.
This is so that any executed commands
that use sockets to connect with other systems
(such as fetching source files from
external CVS repository specifications like
<literal>:pserver:anonymous@cvs.sourceforge.net:/cvsroot/scons</literal>)
will work on Windows systems.
</summary>
</scons_function>

<scons_function name="Prepend">
<arguments signature="env">
(key=val, [...])
</arguments>
<summary>
Appends the specified keyword arguments
to the beginning of construction variables in the environment.
If the Environment does not have
the specified construction variable,
it is simply added to the environment.
If the values of the construction variable
and the keyword argument are the same type,
then the two values will be simply added together.
Otherwise, the construction variable
and the value of the keyword argument
are both coerced to lists,
and the lists are added together.
(See also the Append method, above.)

Example:

<example>
env.Prepend(CCFLAGS = '-g ', FOO = ['foo.yyy'])
</example>
</summary>
</scons_function>

<scons_function name="PrependENVPath">
<arguments signature="env">
(name, newpath, [envname, sep, delete_existing])
</arguments>
<summary>
This appends new path elements to the given path in the
specified external environment
(&cv-ENV;
by default).
This will only add
any particular path once (leaving the first one it encounters and
ignoring the rest, to preserve path order),
and to help assure this,
will normalize all paths (using
<literal>os.path.normpath</literal>
and
<literal>os.path.normcase</literal>).
This can also handle the
case where the given old path variable is a list instead of a
string, in which case a list will be returned instead of a string.

If
<varname>delete_existing</varname>
is 0, then adding a path that already exists
will not move it to the beginning;
it will stay where it is in the list.

Example:

<example>
print 'before:',env['ENV']['INCLUDE']
include_path = '/foo/bar:/foo'
env.PrependENVPath('INCLUDE', include_path)
print 'after:',env['ENV']['INCLUDE']
</example>

The above example will print:

<example>
before: /biz:/foo
after: /foo/bar:/foo:/biz
</example>
</summary>
</scons_function>

<scons_function name="PrependUnique">
<arguments signature="env">
(key=val, delete_existing=0, [...])
</arguments>
<summary>
Appends the specified keyword arguments
to the beginning of construction variables in the environment.
If the Environment does not have
the specified construction variable,
it is simply added to the environment.
If the construction variable being appended to is a list,
then any value(s) that already exist in the
construction variable will
<emphasis>not</emphasis>
be added again to the list.
However, if delete_existing is 1, 
existing matching values are removed first, so
existing values in the arg list move to the front of the list.

Example:

<example>
env.PrependUnique(CCFLAGS = '-g', FOO = ['foo.yyy'])
</example>
</summary>
</scons_function>

<scons_function name="Replace">
<arguments signature="env">
(key=val, [...])
</arguments>
<summary>
Replaces construction variables in the Environment
with the specified keyword arguments.

Example:

<example>
env.Replace(CCFLAGS = '-g', FOO = 'foo.xxx')
</example>
</summary>
</scons_function>

<scons_function name="Repository">
<arguments>
(directory)
</arguments>
<summary>
Specifies that
<varname>directory</varname>
is a repository to be searched for files.
Multiple calls to
&f-Repository;
are legal,
and each one adds to the list of
repositories that will be searched.

To
&scons;,
a repository is a copy of the source tree,
from the top-level directory on down,
which may contain
both source files and derived files
that can be used to build targets in
the local source tree.
The canonical example would be an
official source tree maintained by an integrator.
If the repository contains derived files,
then the derived files should have been built using
&scons;,
so that the repository contains the necessary
signature information to allow
&scons;
to figure out when it is appropriate to
use the repository copy of a derived file,
instead of building one locally.

Note that if an up-to-date derived file
already exists in a repository,
&scons;
will
<emphasis>not</emphasis>
make a copy in the local directory tree.
In order to guarantee that a local copy
will be made,
use the
&f-link-Local;
method.
</summary>
</scons_function>

<scons_function name="Requires">
<arguments>
(target, prerequisite)
</arguments>
<summary>
Specifies an order-only relationship
between the specified target file(s)
and the specified prerequisite file(s).
The prerequisite file(s)
will be (re)built, if necessary,
<emphasis>before</emphasis>
the target file(s),
but the target file(s) do not actually
depend on the prerequisites
and will not be rebuilt simply because
the prerequisite file(s) change.

Example:

<example>
env.Requires('foo', 'file-that-must-be-built-before-foo')
</example>
</summary>
</scons_function>

<scons_function name="Scanner">
<arguments>
(function, [argument, keys, path_function, node_class, node_factory, scan_check, recursive])
</arguments>
<summary>
Creates a Scanner object for
the specified
<varname>function</varname>.
See the section "Scanner Objects,"
below, for a complete explanation of the arguments and behavior.
</summary>
</scons_function>

<scons_function name="SConscriptChdir">
<arguments>
(value)
</arguments>
<summary>
By default,
&scons;
changes its working directory
to the directory in which each
subsidiary SConscript file lives.
This behavior may be disabled
by specifying either:

<example>
SConscriptChdir(0)
env.SConscriptChdir(0)
</example>

in which case
&scons;
will stay in the top-level directory
while reading all SConscript files.
(This may be necessary when building from repositories,
when all the directories in which SConscript files may be found
don't necessarily exist locally.)
You may enable and disable
this ability by calling
SConscriptChdir()
multiple times.

Example:

<example>
env = Environment()
SConscriptChdir(0)
SConscript('foo/SConscript')	# will not chdir to foo
env.SConscriptChdir(1)
SConscript('bar/SConscript')	# will chdir to bar
</example>
</summary>
</scons_function>

<scons_function name="SConsignFile">
<arguments>
([file, dbm_module])
</arguments>
<summary>
This tells
&scons;
to store all file signatures
in the specified database
<varname>file</varname>.
If the
<varname>file</varname>
name is omitted,
<filename>.sconsign</filename>
is used by default.
(The actual file name(s) stored on disk
may have an appropriated suffix appended
by the
<varname> dbm_module</varname>.)
If
<varname>file</varname>
is not an absolute path name,
the file is placed in the same directory as the top-level
&SConstruct;
file.

If
<varname>file</varname>
is
<literal>None</literal>,
then
&scons;
will store file signatures
in a separate
<filename>.sconsign</filename>
file in each directory,
not in one global database file.
(This was the default behavior
prior to SCons 0.96.91 and 0.97.)

The optional
<varname>dbm_module</varname>
argument can be used to specify
which Python database module
The default is to use a custom
<filename>SCons.dblite</filename>
module that uses pickled
Python data structures,
and which works on all Python versions.

Examples:

<example>
# Explicitly stores signatures in ".sconsign.dblite"
# in the top-level SConstruct directory (the
# default behavior).
SConsignFile()

# Stores signatures in the file "etc/scons-signatures"
# relative to the top-level SConstruct directory.
SConsignFile("etc/scons-signatures")

# Stores signatures in the specified absolute file name.
SConsignFile("/home/me/SCons/signatures")

# Stores signatures in a separate .sconsign file
# in each directory.
SConsignFile(None)
</example>
</summary>
</scons_function>

<scons_function name="SetDefault">
<arguments signature="env">
(key=val, [...])
</arguments>
<summary>
Sets construction variables to default values specified with the keyword
arguments if (and only if) the variables are not already set.
The following statements are equivalent:

<example>
env.SetDefault(FOO = 'foo')

if 'FOO' not in env: env['FOO'] = 'foo'
</example>
</summary>
</scons_function>

<scons_function name="SideEffect">
<arguments>
(side_effect, target)
</arguments>
<summary>
Declares
<varname>side_effect</varname>
as a side effect of building
<varname>target</varname>.
Both
<varname>side_effect</varname>
and
<varname>target</varname>
can be a list, a file name, or a node.
A side effect is a target file that is created or updated
as a side effect of building other targets.
For example, a Windows PDB
file is created as a side effect of building the .obj
files for a static library,
and various log files are created updated
as side effects of various TeX commands.
If a target is a side effect of multiple build commands,
&scons;
will ensure that only one set of commands
is executed at a time.
Consequently, you only need to use this method
for side-effect targets that are built as a result of
multiple build commands.

Because multiple build commands may update
the same side effect file,
by default the
<varname>side_effect</varname>
target is
<emphasis>not</emphasis>
automatically removed
when the
<varname>target</varname>
is removed by the
<option>-c</option>
option.
(Note, however, that the
<varname>side_effect</varname>
might be removed as part of
cleaning the directory in which it lives.)
If you want to make sure the
<varname>side_effect</varname>
is cleaned whenever a specific
<varname>target</varname>
is cleaned,
you must specify this explicitly
with the
&f-link-Clean;
or
&f-env-Clean;
function.
</summary>
</scons_function>

<scons_function name="SourceCode">
<arguments>
(entries, builder)
</arguments>
<summary>
This function and its associate factory functions are deprecated.
There is no replacement.
The intended use was to keep a local tree in sync with an archive,
but in actuality the function only causes the archive
to be fetched on the first run.
Synchronizing with the archive is best done external to &SCons;.

Arrange for non-existent source files to
be fetched from a source code management system
using the specified
<varname>builder</varname>.
The specified
<varname>entries</varname>
may be a Node, string or list of both,
and may represent either individual
source files or directories in which
source files can be found.

For any non-existent source files,
&scons;
will search up the directory tree
and use the first
&f-SourceCode;
builder it finds.
The specified
<varname>builder</varname>
may be
<literal>None</literal>,
in which case
&scons;
will not use a builder to fetch
source files for the specified
<varname>entries</varname>,
even if a
&f-SourceCode;
builder has been specified
for a directory higher up the tree.

&scons;
will, by default,
fetch files from SCCS or RCS subdirectories
without explicit configuration.
This takes some extra processing time
to search for the necessary
source code management files on disk.
You can avoid these extra searches
and speed up your build a little
by disabling these searches as follows:

<example>
env.SourceCode('.', None)
</example>

Note that if the specified
<varname>builder</varname>
is one you create by hand,
it must have an associated
construction environment to use
when fetching a source file.

&scons;
provides a set of canned factory
functions that return appropriate
Builders for various popular
source code management systems.
Canonical examples of invocation include:

<example>
env.SourceCode('.', env.BitKeeper('/usr/local/BKsources'))
env.SourceCode('src', env.CVS('/usr/local/CVSROOT'))
env.SourceCode('/', env.RCS())
env.SourceCode(['f1.c', 'f2.c'], env.SCCS())
env.SourceCode('no_source.c', None)
</example>
<!-- env.SourceCode('.', env.Subversion('file:///usr/local/Subversion')) -->
</summary>
</scons_function>

<scons_function name="SourceSignatures">
<arguments>
(type)
</arguments>
<summary>
Note:  Although it is not yet officially deprecated,
use of this function is discouraged.
See the
&f-link-Decider;
function for a more flexible and straightforward way
to configure SCons' decision-making.

The
&f-SourceSignatures;
function tells
&scons;
how to decide if a source file
(a file that is not built from any other files)
has changed since the last time it
was used to build a particular target file.
Legal values are
<literal>MD5</literal>
or
<literal>timestamp</literal>.

If the environment method is used,
the specified type of source signature
is only used when deciding whether targets
built with that environment are up-to-date or must be rebuilt.
If the global function is used,
the specified type of source signature becomes the default
used for all decisions
about whether targets are up-to-date.

<literal>MD5</literal>
means
&scons;
decides that a source file has changed
if the MD5 checksum of its contents has changed since
the last time it was used to rebuild a particular target file.

<literal>timestamp</literal>
means
&scons;
decides that a source file has changed
if its timestamp (modification time) has changed since
the last time it was used to rebuild a particular target file.
(Note that although this is similar to the behavior of Make,
by default it will also rebuild if the dependency is
<emphasis>older</emphasis>
than the last time it was used to rebuild the target file.)

There is no different between the two behaviors
for Python
&f-Value;
node objects.

<literal>MD5</literal>
signatures take longer to compute,
but are more accurate than
<literal>timestamp</literal>
signatures.
The default value is
<literal>MD5</literal>.

Note that the default
&f-link-TargetSignatures;
setting (see below)
is to use this
&f-SourceSignatures;
setting for any target files that are used
to build other target files.
Consequently, changing the value of
&f-SourceSignatures;
will, by default,
affect the up-to-date decision for all files in the build
(or all files built with a specific construction environment
when
&f-env-SourceSignatures;
is used).
</summary>
</scons_function>

<scons_function name="Split">
<arguments>
(arg)
</arguments>
<summary>
Returns a list of file names or other objects.
If arg is a string,
it will be split on strings of white-space characters
within the string,
making it easier to write long lists of file names.
If arg is already a list,
the list will be returned untouched.
If arg is any other type of object,
it will be returned as a list
containing just the object.

Example:

<example>
files = Split("f1.c f2.c f3.c")
files = env.Split("f4.c f5.c f6.c")
files = Split("""
	f7.c
	f8.c
	f9.c
""")
</example>
</summary>
</scons_function>

<scons_function name="subst">
<arguments signature="env">
(input, [raw, target, source, conv])
</arguments>
<summary>
Performs construction variable interpolation
on the specified string or sequence argument
<varname>input</varname>.

By default,
leading or trailing white space will
be removed from the result.
and all sequences of white space
will be compressed to a single space character.
Additionally, any
<literal>$(</literal>
and
<literal>$)</literal>
character sequences will be stripped from the returned string,
The optional
<varname>raw</varname>
argument may be set to
<literal>1</literal>
if you want to preserve white space and
<literal>$(</literal>-<literal>$)</literal>
sequences.
The
<varname>raw</varname>
argument may be set to
<literal>2</literal>
if you want to strip
all characters between
any
<literal>$(</literal>
and
<literal>$)</literal>
pairs
(as is done for signature calculation).

If the input is a sequence
(list or tuple),
the individual elements of
the sequence will be expanded,
and the results will be returned as a list.

The optional
<varname>target</varname>
and
<varname>source</varname>
keyword arguments
must be set to lists of
target and source nodes, respectively,
if you want the
&cv-TARGET;,
&cv-TARGETS;,
&cv-SOURCE;
and
&cv-SOURCES;
to be available for expansion.
This is usually necessary if you are
calling
&f-env-subst;
from within a Python function used
as an SCons action.

Returned string values or sequence elements
are converted to their string representation by default.
The optional
<varname>conv</varname>
argument
may specify a conversion function
that will be used in place of
the default.
For example, if you want Python objects
(including SCons Nodes)
to be returned as Python objects,
you can use the Python
&lambda;
idiom to pass in an unnamed function
that simply returns its unconverted argument.

Example:

<example>
print env.subst("The C compiler is: $CC")

def compile(target, source, env):
    sourceDir = env.subst("${SOURCE.srcdir}",
                          target=target,
                          source=source)

source_nodes = env.subst('$EXPAND_TO_NODELIST',
                         conv=lambda x: x)
</example>
</summary>
</scons_function>

<scons_function name="TargetSignatures">
<arguments>
(type)
</arguments>
<summary>
Note:  Although it is not yet officially deprecated,
use of this function is discouraged.
See the
&f-link-Decider;
function for a more flexible and straightforward way
to configure SCons' decision-making.

The
&f-TargetSignatures;
function tells
&scons;
how to decide if a target file
(a file that
<emphasis>is</emphasis>
built from any other files)
has changed since the last time it
was used to build some other target file.
Legal values are
<literal>"build"</literal>;
<literal>"content"</literal>
(or its synonym
<literal>"MD5"</literal>);
<literal>"timestamp"</literal>;
or
<literal>"source"</literal>.

If the environment method is used,
the specified type of target signature is only used
for targets built with that environment.
If the global function is used,
the specified type of signature becomes the default
used for all target files that
don't have an explicit target signature type
specified for their environments.

<literal>"content"</literal>
(or its synonym
<literal>"MD5"</literal>)
means
&scons;
decides that a target file has changed
if the MD5 checksum of its contents has changed since
the last time it was used to rebuild some other target file.
This means
&scons;
will open up
MD5 sum the contents
of target files after they're built,
and may decide that it does not need to rebuild
"downstream" target files if a file was
rebuilt with exactly the same contents as the last time.

<literal>"timestamp"</literal>
means
&scons;
decides that a target file has changed
if its timestamp (modification time) has changed since
the last time it was used to rebuild some other target file.
(Note that although this is similar to the behavior of Make,
by default it will also rebuild if the dependency is
<emphasis>older</emphasis>
than the last time it was used to rebuild the target file.)

<literal>"source"</literal>
means
&scons;
decides that a target file has changed
as specified by the corresponding
&f-SourceSignatures;
setting
(<literal>"MD5"</literal>
or
<literal>"timestamp"</literal>).
This means that
&scons;
will treat all input files to a target the same way,
regardless of whether they are source files
or have been built from other files.

<literal>"build"</literal>
means
&scons;
decides that a target file has changed
if it has been rebuilt in this invocation
or if its content or timestamp have changed
as specified by the corresponding
&f-SourceSignatures;
setting.
This "propagates" the status of a rebuilt file
so that other "downstream" target files
will always be rebuilt,
even if the contents or the timestamp
have not changed.

<literal>"build"</literal>
signatures are fastest because
<literal>"content"</literal>
(or
<literal>"MD5"</literal>)
signatures take longer to compute,
but are more accurate than
<literal>"timestamp"</literal>
signatures,
and can prevent unnecessary "downstream" rebuilds
when a target file is rebuilt to the exact same contents
as the previous build.
The
<literal>"source"</literal>
setting provides the most consistent behavior
when other target files may be rebuilt from
both source and target input files.
The default value is
<literal>"source"</literal>.

Because the default setting is
<literal>"source"</literal>,
using
&f-SourceSignatures;
is generally preferable to
&f-TargetSignatures;,
so that the up-to-date decision
will be consistent for all files
(or all files built with a specific construction environment).
Use of
&f-TargetSignatures;
provides specific control for how built target files
affect their "downstream" dependencies.
</summary>
</scons_function>

<scons_function name="Tool">
<arguments>
(string, [toolpath, **kw])
</arguments>
<summary>
The
&f-Tool;
form of the function
returns a callable object
that can be used to initialize
a construction environment using the
tools keyword of the Environment() method.
The object may be called with a construction
environment as an argument,
in which case the object will
add the necessary variables
to the construction environment
and the name of the tool will be added to the
&cv-link-TOOLS;
construction variable.

Additional keyword arguments are passed to the tool's
<function>generate</function>()
method.

Examples:

<example>
env = Environment(tools = [ Tool('msvc') ])

env = Environment()
t = Tool('msvc')
t(env)  # adds 'msvc' to the TOOLS variable
u = Tool('opengl', toolpath = ['tools'])
u(env)  # adds 'opengl' to the TOOLS variable
</example>

The
&f-env-Tool;
form of the function
applies the callable object for the specified tool
<varname>string</varname>
to the environment through which the method was called.

Additional keyword arguments are passed to the tool's
<function>generate</function>()
method.

<example>
env.Tool('gcc')
env.Tool('opengl', toolpath = ['build/tools'])
</example>
</summary>
</scons_function>

<scons_function name="Value">
<arguments>
(value, [built_value])
</arguments>
<summary>
Returns a Node object representing the specified Python value.  Value
Nodes can be used as dependencies of targets.  If the result of
calling
<function>str</function>(<varname>value</varname>)
changes between SCons runs, any targets depending on
<function>Value</function>(<varname>value</varname>)
will be rebuilt.
(This is true even when using timestamps to decide if
files are up-to-date.)
When using timestamp source signatures, Value Nodes'
timestamps are equal to the system time when the Node is created.

The returned Value Node object has a
<function>write</function>()
method that can be used to "build" a Value Node
by setting a new value.
The optional
<varname>built_value</varname>
argument can be specified
when the Value Node is created
to indicate the Node should already be considered
"built."
There is a corresponding
<function>read</function>()
method that will return the built value of the Node.

Examples:

<example>
env = Environment()

def create(target, source, env):
    # A function that will write a 'prefix=$SOURCE'
    # string into the file name specified as the
    # $TARGET.
    f = open(str(target[0]), 'wb')
    f.write('prefix=' + source[0].get_contents())

# Fetch the prefix= argument, if any, from the command
# line, and use /usr/local as the default.
prefix = ARGUMENTS.get('prefix', '/usr/local')

# Attach a .Config() builder for the above function action
# to the construction environment.
env['BUILDERS']['Config'] = Builder(action = create)
env.Config(target = 'package-config', source = Value(prefix))

def build_value(target, source, env):
    # A function that "builds" a Python Value by updating
    # the the Python value with the contents of the file
    # specified as the source of the Builder call ($SOURCE).
    target[0].write(source[0].get_contents())

output = env.Value('before')
input = env.Value('after')

# Attach a .UpdateValue() builder for the above function
# action to the construction environment.
env['BUILDERS']['UpdateValue'] = Builder(action = build_value)
env.UpdateValue(target = Value(output), source = Value(input))
</example>
</summary>
</scons_function>

<scons_function name="VariantDir">
<arguments>
(variant_dir, src_dir, [duplicate])
</arguments>
<summary>
Use the
&f-VariantDir;
function to create a copy of your sources in another location:
if a name under
<varname>variant_dir</varname>
is not found but exists under
<varname>src_dir</varname>,
the file or directory is copied to
<varname>variant_dir</varname>.
Target files can be built in a different directory
than the original sources by simply refering to the sources (and targets)
within the variant tree.

&f-VariantDir;
can be called multiple times with the same
<varname>src_dir</varname>
to set up multiple builds with different options
(<varname>variants</varname>).
The
<varname>src_dir</varname>
location must be in or underneath the SConstruct file's directory, and
<varname>variant_dir</varname>
may not be underneath
<varname>src_dir</varname>.
<!--
TODO: Can the above restrictions be clarified or relaxed?
TODO: The latter restriction is clearly not completely right;
TODO: src_dir = '.' works fine with a build dir under it.
-->

The default behavior is for
&scons;
to physically duplicate the source files in the variant tree.
Thus, a build performed in the variant tree is guaranteed to be identical
to a build performed in the source tree even if
intermediate source files are generated during the build,
or preprocessors or other scanners search for included files
relative to the source file,
or individual compilers or other invoked tools are hard-coded
to put derived files in the same directory as source files.

If possible on the platform,
the duplication is performed by linking rather than copying;
see also the
<option>--duplicate</option>
command-line option.
Moreover, only the files needed for the build are duplicated;
files and directories that are not used are not present in
<varname>variant_dir</varname>.

Duplicating the source tree may be disabled by setting the
<literal>duplicate</literal>
argument to
<literal>0</literal>
(zero).
This will cause
&scons;
to invoke Builders using the path names of source files in
<varname>src_dir</varname>
and the path names of derived files within
<varname>variant_dir</varname>.
This is always more efficient than
<literal>duplicate=1</literal>,
and is usually safe for most builds
(but see above for cases that may cause problems).

Note that
&f-VariantDir;
works most naturally with a subsidiary SConscript file.
However, you would then call the subsidiary SConscript file
not in the source directory, but in the
<varname>variant_dir</varname>,
regardless of the value of
<literal>duplicate</literal>.
This is how you tell
&scons;
which variant of a source tree to build:

<example>
# run src/SConscript in two variant directories
VariantDir('build/variant1', 'src')
SConscript('build/variant1/SConscript')
VariantDir('build/variant2', 'src')
SConscript('build/variant2/SConscript')
</example>

See also the
&f-link-SConscript;
function, described above,
for another way to specify a variant directory
in conjunction with calling a subsidiary SConscript file.

Examples:

<example>
# use names in the build directory, not the source directory
VariantDir('build', 'src', duplicate=0)
Program('build/prog', 'build/source.c')
</example>

<example>
# this builds both the source and docs in a separate subtree
VariantDir('build', '.', duplicate=0)
SConscript(dirs=['build/src','build/doc'])
</example>

<example>
# same as previous example, but only uses SConscript
SConscript(dirs='src', variant_dir='build/src', duplicate=0)
SConscript(dirs='doc', variant_dir='build/doc', duplicate=0)
</example>
</summary>
</scons_function>

<scons_function name="WhereIs">
<arguments>
(program, [path, pathext, reject])
</arguments>
<summary>
Searches for the specified executable
<varname>program</varname>,
returning the full path name to the program
if it is found,
and returning None if not.
Searches the specified
<varname>path</varname>,
the value of the calling environment's PATH
(<literal>env['ENV']['PATH']</literal>),
or the user's current external PATH
(<literal>os.environ['PATH']</literal>)
by default.
On Windows systems, searches for executable
programs with any of the file extensions
listed in the specified
<varname>pathext</varname>,
the calling environment's PATHEXT
(<literal>env['ENV']['PATHEXT']</literal>)
or the user's current PATHEXT
(<literal>os.environ['PATHEXT']</literal>)
by default.
Will not select any
path name or names
in the specified
<varname>reject</varname>
list, if any.
</summary>
</scons_function>