Author maggyero
Recipients barry, eric.smith, eric.snow, maggyero, ned.deily, nedbat
Date 2018-11-23.00:00:21
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@barry You gave 2 reasons for changing __spec__.origin and __file__ for namespace packages.

Your 1st reason:

> I don't particularly like that its origin is "namespace".  That's an odd special case that's unhelpful to test against (what if you import a non-namespace package from the directory "namespace"?)

As far as I know, a non-namespace package always has an file, so if it is imported from a directory named "namespace" it has a __spec__.origin and __file__ attributes equal to "path/to/package/namespace/". So I don’t see the problem here with having a "namespace" origin for namespace package specs.

In addition, PEP 420 that introduced implicit namespace packages in Python 3.3 clearly stated that having no __file__ attribute was intended for namespace packages, and more generally was left a the discretion of the module’s loader and no more limited to built-in modules (

> Previously, module reprs were hard coded based on assumptions about a module's __file__ attribute. If this attribute existed and was a string, it was assumed to be a file system path, and the module object's repr would include this in its value. The only exception was that PEP 302 reserved missing __file__ attributes to built-in modules, and in CPython, this assumption was baked into the module object's implementation. Because of this restriction, some modules contained contrived __file__ values that did not reflect file system paths, and which could cause unexpected problems later (e.g. os.path.join() on a non-path __file__ would return gibberish).
> This PEP relaxes this constraint, and leaves the setting of __file__ to the purview of the loader producing the module. Loaders may opt to leave __file__ unset if no file system path is appropriate. Loaders may also set additional reserved attributes on the module if useful. This means that the definitive way to determine the origin of a module is to check its __loader__ attribute.
> For example, namespace packages as described in this PEP will have no __file__ attribute because no corresponding file exists.

Your 2nd reason:

> This is especially bad because the documentation for __spec__.origin implies a correlation to __file__, and says:
> "Name of the place from which the module is loaded, e.g. “builtin” for built-in modules and the filename for modules loaded from source. Normally “origin” should be set, but it may be None (the default) which indicates it is unspecified."

I agree here, so why not updating the documentation instead of changing the implementation which followed PEP 420?
Date User Action Args
2018-11-23 00:00:21maggyerosetrecipients: + maggyero, barry, eric.smith, nedbat, ned.deily, eric.snow
2018-11-23 00:00:21maggyerosetmessageid: <>
2018-11-23 00:00:21maggyerolinkissue32305 messages
2018-11-23 00:00:21maggyerocreate