How do I constrain the SCons Command builder to run only if its dependencies have changed?

Posted by saffsd on Stack Overflow See other posts from Stack Overflow or by saffsd
Published on 2009-05-06T04:53:18Z Indexed on 2010/03/25 3:03 UTC
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python

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scons

I am using the Command builder in scons to specify that a particular script needs to be invoked to produce a particular file.

I would like to only run the script if it has been modified since the file was previously generated. The default behaviour of the Command builder seems to be to always run the script. How can I change this?

This is my current SConstruct:

speed = Command('speed_analysis.tex','','python code/speed.py')
report = PDF(target = 'report.pdf', source = 'report.tex')
Depends(report, speed)

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