[Python-Dev] Think a dead import finding script would be handy? (original) (raw)
Christian Heimes lists at cheimes.de
Sun Aug 17 23:12:52 CEST 2008
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Brett Cannon wrote:
After Christian mentioned how we could speed up interpreter start-up by removing some dead imports he found, I decided to write up a quick script that generates the AST for a source file and (very roughly) tries to find imports that are never used. People think it's worth tossing into Tools, even if it is kind of rough? Otherwise I might toss it into the sandbox or make a quick Google code project out of it.
Regardless, one interesting side-effect of the script is that beyond finding some extraneous imports in various places, it also found some holes in all. I have the script look for the definition of all and consider an import used if it is listed there.
Zope 3 has various tools for sorting imports or checking for unused imports. See http://svn.zope.org/Zope3/trunk/utilities/
Python 3.0 currently imports 25 modules on startup, Python 2.6 just 14:
./python -S -c "import sys; print(list(sorted(sys.modules)), len(sys.modules))"
['main', '_abcoll', '_codecs', '_fileio', '_thread', '_weakref', '_weakrefset', 'abc', 'builtins', 'codecs', 'copyreg', 'encodings', 'encodings.aliases', 'encodings.latin_1', 'encodings.utf_8', 'errno', 'genericpath', 'io', 'os', 'os.path', 'posix', 'posixpath', 'signal', 'stat', 'sys', 'zipimport'] 26
_abcoll os.envirion uses _abcoll.MutableMapping
_weakref + _weakrefset imported for abc
abc imported for io.IOBase
copyreg imported by os to register some pickle handlers. Could be removed by placing the code into copyreg instead.
encodings.* imported early to avoid various bootstrapping issues (IIRC)
encodings.aliases: Could be removing by delaying the import until search_function() is called the first time
errno, genericpath, posix, posixpath, stat: import by os and os.path
stat: Could probably be replaced by a simple and faster C implementation in posixmodule.c to spare the import
signal: I'm not sure why the module is loaded at all.
I think we can get rid of copyreg and encodings.aliases easily.
Christian
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