On 12/07/2010 22:59, Antoine Pitrou wrote:
On Mon, 12 Jul 2010 17:47:31 -0400
Fred Drake<fdr...@acm.org> wrote:
On Mon, Jul 12, 2010 at 5:42 PM, Michael Foord
<fuzzy...@voidspace.org.uk> wrote:
I'm sure Brett will love this idea, but if it was impossible to reimport the
script being executed as __main__ with a different name it would solve these
problems.
Indeed! And I'd be quite content with such a solution, since I
consider scripts and modules to be distinct.
Except that modules can often be executed as scripts...
Allowing a module-executed-as-script to be in sys.modules twice with
different names and classes is still a recipe for problems. For example
see this blog entry from Phil Hassey, an experienced Python developer,
caused by this issue:
http://www.philhassey.com/blog/2009/07/16/oddball-python-252-import-issue/
For scripts that need to be in sys.modules with their "real" name (e.g.
modules executed with python -m) the following trivial workaround is
possible:
if __name__ == '__main__':
sys.modules[real_name] = sys.modules['__main__']
That avoids the problem of error messages like:
TypeError: unbound method foo() must be called with A instance as first
argument (got A instance instead)
(Two different classes with the same name created - one from __main__
and one from real_name.) Use cases for *genuinely* reimporting the same
module with different names (as different module objects rather than
aliases) are relatively rare, and the problem of modules *accidentally*
reimporting themselves not that rare.
All the best,
Michael
Antoine.
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