PyScons 1.0.12

An extension to Scons which enables dependency tracking on python script imports.

PyScons is a tool which works with Scons. It is installed into a new environment with either of the two commands:

from pyscons import PYTOOL
env = Environment(tools = ['default', PYTOOL()])

or:

from pyscons import PYTOOL
env = Environment()
PYTOOL()(env)

This does two things:

1. Installs a new builder: PyScript.

2. Installs a new scanner for python scripts.

PyScript

This Builder has a few additional abilities.

First, it will automatically find the “.py” files referred to when running a module as a script with the ‘-m’ option. For example the following code will run a module as script and add the appriate files to the dependencies:

env.PyScript("out", ["-m timeit", "myscript.py"], "python $SOURCES > $TARGET")

Second, it defaults the command string to “python $SOURCES” and using the “capture” keyword argument, can automatically append the appropriate strings to capture the output or error (or both) to the targets:

env.PyScript("out", ["-m timeit", "myscript.py"], capture="output")

or to capture both the output and error:

env.PyScript(["out","err"], ["-m timeit", "myscript.py"], capture="both")

Just like Command, multiple steps can be used to create a file:

env.PyScript("out", ["step1.py", "step2.py"],
     ["python ${SOURCES[0]} > temp", "python ${SOURCES[1]} > $TARGET", Delete("temp")])

PyScanner

This scanner uses the modulefinder module to find all import dependencies in all sources with a ‘py’ extension. It can take two options in its constructor:

1. filter_path: a callable object (or None) which takes a path as input and returns true if this file should be included as a dependency by scons, or false if it should be ignored. By default, this variable becomes a function which ensures that no system python modules or modules from site-packages are tracked. To track all files, use “lambda p: True”.

2. recursive: with a true (default) or false, it enables or disables recursive dependency tracking.

For example to track all files (including system imports) in a nonrecursive scanner, use the following install code in your SConstruct:

from pyscons import PYTOOL
env = Environment(tools = ['default', PYTOOL(recursive = False, filter_path = lambda p: True)])

Author

19. Joshua Swamidass (homepage)