zipimporter misses namespace packages for implicit dirs #80921

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1. jaraco commented on Apr 27, 2019

   

   jaraco

   on Apr 27, 2019

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   As discovered in pypa/packaging-problems#212, if a PEP-420 namespace package is represented by an implicit directory (that is, there's no explicit entry for the directory, only entries for the contents of the directory), that directory won't be picked up as a namespace package. The following code illustrates the issue:

   zp $ cat make-pkgs.py                                                                                                                                                          
   import zipfile
   
   
   def make_pkgs():
       zf = zipfile.ZipFile('simple.zip', 'w')
       zf.writestr('pkg/__init__.py', b'')
       zf.close()
   
       zf = zipfile.ZipFile('namespace.zip', 'w')
       zf.writestr('ns/pkg/__init__.py', b'')
       zf.close()
   
   
   __name__ == '__main__' and make_pkgs()
   zp $ python make-pkgs.py                                                                                                                                                       
   zp $ env PYTHONPATH=simple.zip python3.7 -c "import pkg"                                                                                                                       
   zp $ env PYTHONPATH=namespace.zip python3.7 -c "import ns.pkg"                                                                                                                 
   Traceback (most recent call last):
     File "<string>", line 1, in <module>
   ModuleNotFoundError: No module named 'ns'
   

   As you can see, in simple.zip, the pkg directory is implied, but despite that condition, pkg is importable.

   However, with namespace.zip, the name ns is not visible even though it's present in the zipfile and would be importable if that zipfile were extracted to a file system.

   zp $ unzip namespace.zip
   Archive:  namespace.zip
    extracting: ns/pkg/__init__.py
   zp $ python3.7 -c "import ns.pkg" && echo done
   done
   

   If you were to reconstruct that zip file on the file system using standard tools or explicitly include 'ns/' in the zip entries, the namespace package becomes visible:

   zp $ rm namespace.zip                                                                                                                                                          
   zp $ zip -r namespace.zip ns                                                                                                                                                   
     adding: ns/ (stored 0%)
     adding: ns/pkg/ (stored 0%)
     adding: ns/pkg/__init__.py (stored 0%)
     adding: ns/pkg/__pycache__/ (stored 0%)
     adding: ns/pkg/__pycache__/__init__.cpython-37.pyc (deflated 23%)
   zp $ rm -r ns                                                                                                                                                                  
   zp $ env PYTHONPATH=namespace.zip python3.7 -c "import ns.pkg" && echo done                                                                                                    
   done
   

   For consistency, the zip import logic should probably honor implicit directories in zip files.
2. jaraco

   added

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Apr 27, 2019
3. ericvsmith commented on Apr 28, 2019

   

   ericvsmith

   on Apr 28, 2019

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   This is a duplicate of bpo-14905.
4. jaraco

   closed this as completedon Apr 28, 2019
5. ezio-melotti

   transferred this issue fromon Apr 10, 2022