leazen at uol.com.ar
Wed Feb 26 15:50:08 CET 2003
Steven Taschuk wrote:
> Quoth Leazen:
>> I'm trying to load modules dinamically. All modules which define a
>>class (Plugin) should be imported and an object of the class within them
>>created, do you think using __import__ is the way to go or that I should
>> Thanks again, first time doing this kind of thing.
> Hm. Never done this sort of thing, but here's my first
> impressions, for what they're worth:
> I assume you've got a plugins directory somewhere that your app
> knows about, and you want to spin through all the *.py files in
> that directory, loading each, and instantiating each module's
> Plugin class, if it defines one. Is this correct?
> If so, I'm not sure __import__ is best. For one thing, I think
> it'll go wandering off on sys.path looking for the specified
> module; but you already know where the file is. The facilities
> provided by the imp module might serve better.
> Here's a quicky illustration. (I hope those more familiar than I
> with this subject will offer comments.)
> Two trivial plugin files:
> $ python loader.py
> Instantiating plugin from <module 'plugin1' from './plugin1.pyc'>
> plugin1 instantiated
> Instantiating plugin from <module 'plugin2' from './plugin2.pyc'>
> plugin2 instantiated
> No plugin in <module 'loader' from './loader.pyc'>
> I'm plugin1!
> I'm plugin2!
> Seems to work, anyway.
> Some caveats:
> - The loader should look for *.pyc and *.pyo files too. Maybe even
> *.so files.
> - The documentation says that imp.load_module() will do a reload if
> the module has already been loaded; this might not be desirable.
> I'm not sure how to prevent it, short of spinning through
> - The error handling is clumsy and probably wrong.
> - There's no support for package structures in the plugin directory.
Thank you for this excelent reply!
- '.so' files? As in shared libraries?
- If the reloading is a problem I'll take care of that after it works.
I also thought about sys.modules.
- I would need to load a package structure a node at a time. I think I
can use the module.__path__ attribute to get the path for each node.
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