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Diffstat (limited to 'doc/user/builders-commands.in')
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diff --git a/doc/user/builders-commands.in b/doc/user/builders-commands.in new file mode 100644 index 0000000..687d12d --- /dev/null +++ b/doc/user/builders-commands.in @@ -0,0 +1,156 @@ +<!-- + + 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. + +--> + + <!-- + + =head2 The C<Command> method + + + The C<Command> method is called as follows: + + Command $env <target>, <inputs>, <build action>; + + The target is made dependent upon the list of input files specified, and the + inputs must be built successfully or Cons will not attempt to build the + target. + + To specify a command with multiple targets, you can specify a reference to a + list of targets. In Perl, a list reference can be created by enclosing a + list in square brackets. Hence the following command: + + Command $env ['foo.h', 'foo.c'], 'foo.template', q( + gen %1 + ); + + could be used in a case where the command C<gen> creates two files, both + F<foo.h> and F<foo.c>. + + --> + + <para> + + Creating a &Builder; and attaching it to a &consenv; + allows for a lot of flexibility when you + want to re-use actions + to build multiple files of the same type. + This can, however, be cumbersome + if you only need to execute one specific command + to build a single file (or group of files). + For these situations, &SCons; supports a + &Command; &Builder; that arranges + for a specific action to be executed + to build a specific file or files. + This looks a lot like the other builders + (like &b-link-Program;, &b-link-Object;, etc.), + but takes as an additional argument + the command to be executed to build the file: + + </para> + + <scons_example name="ex1"> + <file name="SConstruct" printme="1"> + env = Environment() + env.Command('foo.out', 'foo.in', "sed 's/x/y/' < $SOURCE > $TARGET") + </file> + <file name="foo.in"> + foo.in + </file> + </scons_example> + + <para> + + When executed, + &SCons; runs the specified command, + substituting &cv-link-SOURCE; and &cv-link-TARGET; + as expected: + + </para> + + <scons_output example="ex1"> + <scons_output_command>scons -Q</scons_output_command> + </scons_output> + + <para> + + This is often more convenient than + creating a &Builder; object + and adding it to the &cv-link-BUILDERS; variable + of a &consenv; + + </para> + + <para> + + Note that the action you specify to the + &Command; &Builder; can be any legal &SCons; &Action;, + such as a Python function: + + </para> + + <scons_example name="ex2"> + <file name="SConstruct" printme="1"> + env = Environment() + def build(target, source, env): + # Whatever it takes to build + return None + env.Command('foo.out', 'foo.in', build) + </file> + <file name="foo.in"> + foo.in + </file> + </scons_example> + + <para> + + Which executes as follows: + + </para> + + <scons_output example="ex2"> + <scons_output_command>scons -Q</scons_output_command> + </scons_output> + + <para> + + Note that &cv-link-SOURCE; and &cv-link-TARGET; are expanded + in the source and target as well as of SCons 1.1, + so you can write: + + </para> + + <scons_example name="ex3"> + <file name="SConstruct" printme="1"> + env.Command('${SOURCE.basename}.out', 'foo.in', build) + </file> + </scons_example> + + + <para> + + which does the same thing as the previous example, but allows you + to avoid repeating yourself. + + </para> + |