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+<!--
+
+ Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 The SCons Foundation
+
+ Permission is hereby granted, free of charge, to any person obtaining
+ a copy of this software and associated documentation files (the
+ "Software"), to deal in the Software without restriction, including
+ without limitation the rights to use, copy, modify, merge, publish,
+ distribute, sublicense, and/or sell copies of the Software, and to
+ permit persons to whom the Software is furnished to do so, subject to
+ the following conditions:
+
+ The above copyright notice and this permission notice shall be included
+ in all copies or substantial portions of the Software.
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
+ KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
+ WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+-->
+
+ <para>
+
+ Configuring the right options to build programs to work with
+ libraries--especially shared libraries--that are available
+ on POSIX systems can be very complicated.
+ To help this situation,
+ various utilies with names that end in <filename>config</filename>
+ return the command-line options for the GNU Compiler Collection (GCC)
+ that are needed to use these libraries;
+ for example, the command-line options
+ to use a library named <filename>lib</filename>
+ would be found by calling a utility named <filename>lib-config</filename>.
+
+ </para>
+
+ <para>
+
+ A more recent convention is that these options
+ are available from the generic <filename>pkg-config</filename> program,
+ which has common framework, error handling, and the like,
+ so that all the package creator has to do is provide the set of strings
+ for his particular package.
+
+ </para>
+
+ <para>
+
+ &SCons; construction environments have a &ParseConfig; method
+ that executes a <filename>*config</filename> utility
+ (either <filename>pkg-config</filename> or a
+ more specific utility)
+ and configures the appropriate construction variables
+ in the environment
+ based on the command-line options
+ returned by the specified command.
+
+ </para>
+
+ <programlisting>
+ env = Environment()
+ env['CPPPATH'] = ['/lib/compat']
+ env.ParseConfig("pkg-config x11 --cflags --libs")
+ print env['CPPPATH']
+ </programlisting>
+
+ <para>
+
+ &SCons; will execute the specified command string,
+ parse the resultant flags,
+ and add the flags to the appropriate environment variables.
+
+ </para>
+
+ <screen>
+ % <userinput>scons -Q</userinput>
+ Package x11 was not found in the pkg-config search path.
+ Perhaps you should add the directory containing `x11.pc'
+ to the PKG_CONFIG_PATH environment variable
+ No package 'x11' found
+ OSError: 'pkg-config x11 --cflags --libs' exited 1:
+ File "/home/my/project/SConstruct", line 3:
+ env.ParseConfig("pkg-config x11 --cflags --libs")
+ File "bootstrap/src/engine/SCons/Environment.py", line 1474:
+ None
+ File "bootstrap/src/engine/SCons/Environment.py", line 593:
+ None
+ </screen>
+
+ <para>
+
+ In the example above, &SCons; has added the include directory to
+ <varname>CPPPATH</varname>.
+ (Depending upon what other flags are emitted by the
+ <filename>pkg-config</filename> command,
+ other variables may have been extended as well.)
+
+ </para>
+
+ <para>
+
+ Note that the options are merged with existing options using
+ the &MergeFlags; method,
+ so that each option only occurs once in the construction variable:
+
+ </para>
+
+ <programlisting>
+ env = Environment()
+ env.ParseConfig("pkg-config x11 --cflags --libs")
+ env.ParseConfig("pkg-config x11 --cflags --libs")
+ print env['CPPPATH']
+ </programlisting>
+
+ <screen>
+ % <userinput>scons -Q</userinput>
+ Package x11 was not found in the pkg-config search path.
+ Perhaps you should add the directory containing `x11.pc'
+ to the PKG_CONFIG_PATH environment variable
+ No package 'x11' found
+ OSError: 'pkg-config x11 --cflags --libs' exited 1:
+ File "/home/my/project/SConstruct", line 2:
+ env.ParseConfig("pkg-config x11 --cflags --libs")
+ File "bootstrap/src/engine/SCons/Environment.py", line 1474:
+ None
+ File "bootstrap/src/engine/SCons/Environment.py", line 593:
+ None
+ </screen>