Can't get compression in Python zip script.

[Scott David Daniels]

Fredrik Lundh wrote:
> M.E.Farmer wrote:
> 
>>I saw compression=0 and assumed that 1 would mean true, but no!
>>zipfile.ZIP_DEFLATED = 8, defies logic, it is the only compression type
>>why not accept any non zero as compression.
> 
> "is the only compression type" ?  quoting from the ZIP specification:
> 
>      compression method: (2 bytes)
>           (see accompanying documentation for algorithm descriptions)
>           0 - The file is stored (no compression)
>           1 - The file is Shrunk
...
>           8 - The file is Deflated
>           9 - Enhanced Deflating using Deflate64(tm)
>          10 - PKWARE Data Compression Library Imploding
>          11 - Reserved by PKWARE
>          12 - File is compressed using BZIP2 algorithm
> ( http://www.pkware.com/company/standards/appnote/appnote.txt )
> the current zipfile version only supports 0 and 8, but that doesn't mean that
> future versions won't support other ZIP compressions.
> 
For example, I am hoping I'll get method 12 into Python 2.5.  Please
don't use the unadorned numbers, however.  Use zipfile.ZIP_STORE,
zipfile.ZIP_DEFLATED, and (later) zipfile.ZIP_BZIP2.  This way you can
catch an exception when using an unimplemented compression format as
you retrieve the compression code, rather than waiting to get into the
midst of compression / decompression before getting a failure.

--Scott David Daniels
Scott.Daniels at Acm.Org