Just as sys.path currently has default directory names, default zip archive names are added too. Otherwise there is no way to import all Python library files from an archive.
A standard for this would be really cool.
Yup.
Suppose import.c generates the path "/A/B/SubDir/Q/R/modfoo.pyc". Then it will also generate the path "/C/D/E/Archive.zip/Q/R/modfoo.pyc". Finding the SubDir path is exactly equivalent to finding "Q/R/modfoo.pyc" in the archive.
So python packages and modules can exists *only* at the top level? That would conflict somewhat with jython where at would be common to put python modules into the same .zip file as java classes and java classes also wants to own the root of a zip file.
In the current implementaion in jython, we can put python modules under any path and add the zipfile!path to sys.path:
sys.path.append("/path/to/zipfile.zip!Lib")
which will look for Lib/Q/R/modfoo.py (and Lib/Q/R/modfoo$py.class) in the archive.
Maybe it's possible to allow "/path/to/zipfile.zip/subdirectory/etc/" in sys.path? That sounds better than picking a random new character as delimiter.
[I found efficiency hard to achieve in jython because opening a zipfile in java also cause the zip index to be read into a dictionary. So we did not want to reopen a zipfile if it can be avoided. Instead we hide a reference to the opened file in sys.path so that when removing a zipfile name from sys.path, the file is eventually closed.]
I don't think Python has this problem, since we have control over the zipfile reading code.
Would entries in the static python dict be removed when a zipfile is removed from sys.path?
It can be arranged that they are removed at some later point (e.g. when sys.path is next searched).
What is the __path__ vrbl set to in a module imported from a zipfile? Can the module make changes to __path__ and will be changes to used when importing submodules?
What value should __file__ have?
IMO these two questions are answered by the pathname semantics that Jim proposes: __file__ = "/C/D/E/Archive.zip/Q/R/modfoo.pyc" and __path__ = ["/C/D/E/Archive.zip/Q/R"]. --Guido van Rossum (home page: http://www.python.org/~guido/)