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<para>
There is a common set of simple tasks that many build configurations rely
on as they become more complex. Most build tools have special
purpose constructs for performing these tasks, but since &SConscript;
files are &Python; scripts, you can use more flexible built-in &Python;
services to perform these tasks. This appendix lists a number of these
tasks and how to implement them in &Python;.
</para>
<example>
<title>Wildcard globbing to create a list of filenames</title>
<programlisting>
files = Glob(wildcard)
</programlisting>
</example>
<example>
<title>Filename extension substitution</title>
<programlisting>
import os.path
filename = os.path.splitext(filename)[0]+extension
</programlisting>
</example>
<example>
<title>Appending a path prefix to a list of filenames</title>
<programlisting>
import os.path
filenames = [os.path.join(prefix, x) for x in filenames]
</programlisting>
<simpara>or in Python 1.5.2:</simpara>
<programlisting>
import os.path
new_filenames = []
for x in filenames:
new_filenames.append(os.path.join(prefix, x))
</programlisting>
</example>
<example>
<title>Substituting a path prefix with another one</title>
<programlisting>
if filename.find(old_prefix) == 0:
filename = filename.replace(old_prefix, new_prefix)
</programlisting>
<simpara>or in Python 1.5.2:</simpara>
<programlisting>
if filename.find(old_prefix) == 0:
filename = filename.replace(old_prefix, new_prefix)
</programlisting>
</example>
<example>
<title>Filtering a filename list to exclude/retain only a specific set
of extensions</title>
<programlisting>
import os.path
filenames = [x for x in filenames if os.path.splitext(x)[1] in extensions]
</programlisting>
<simpara>or in Python 1.5.2:</simpara>
<programlisting>
import os.path
new_filenames = []
for x in filenames:
if os.path.splitext(x)[1] in extensions:
new_filenames.append(x)
</programlisting>
</example>
<example>
<title>The "backtick function": run a shell command and capture the
output</title>
<programlisting>import os
output = os.popen(command).read()
</programlisting>
</example>
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