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<para>
The env.AddMethod(function, [name]) function is used to add a method
to an environment. It's typically used to add a "pseudo-builder" or
wrap up a call to multiple builders. In the first example, we want
to install the program into the standard bin dir, but also copy it
into a local install/bin dir that might be used to build a package
from.
</para>
<scons_example name="ex1">
<file name="SConstruct" printme="1">
def install_in_bin_dirs(env, source):
"""Install source in both bin dirs"""
i1 = env.Install("$BIN", source)
i2 = env.Install("$LOCALBIN", source)
return [i1[0], i2][0] # Return a list, like a normal builder
env = Environment(BIN='/usr/bin', LOCALBIN='#install/bin')
env.AddMethod(install_in_bin_dirs, "InstallInBinDirs")
env.InstallInBinDirs(Program('hello.c')) # installs hello in both bin dirs
</file>
<file name="hello.c">
int main() { printf("Hello, world!\n"); }
</file>
</scons_example>
<para>
This produces the following:
</para>
<scons_output example="ex1">
<scons_output_command>scons -Q /</scons_output_command>
</scons_output>
<para>
It also gives more flexibility in parsing arguments than you can get
with a builder. The next example shows a pseudo-builder with a
named argument that modifies the filename, and a separate argument
for the resource file (rather than having the builder figure it out
by file extension). Also this example demonstrates using the global
AddMethod function to add a method to the global Environment class,
so it will be used in all subsequently created environments.
</para>
<scons_example name="ex2">
<file name="SConstruct" printme="1">
import sys
def BuildTestProg(env, testfile, resourcefile, testdir="tests"):
"""Build the test program;
prepends "test_" to src and target, and puts target into testdir."""
srcfile="test_%s.c"%testfile
if sys.platform=='win32':
target="%s/test_%s$EXESUFFIX"%(testdir,[testfile, resourcefile])
else:
target="%s/test_%s$EXESUFFIX"%(testdir,testfile)
p = env.Program(target, srcfile)
return p
AddMethod(Environment, BuildTestProg)
# Now use it
env=Environment()
env.BuildTestProg('stuff', resourcefile='res.rc')
</file>
<file name="test_stuff.c">
int main() { printf("Hello, world!\n"); }
</file>
</scons_example>
<para>
This produces the following (on Linux, anyway; Windows would include the
resource file):
</para>
<scons_output example="ex2">
<scons_output_command>scons -Q</scons_output_command>
</scons_output>
<para>
Using AddMethod is better than just adding an instance method to an
Environment because it gets called as a proper method, and AddMethod
provides for copying the method to any copies of the Environment
instance.
</para>
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