[Python-Dev] Reintroduce or drop completly hex, bz2, rot13, ... codecs (original) (raw)

Victor Stinner victor.stinner at haypocalc.com
Wed Jun 9 01:53:14 CEST 2010

There are two opposite issues in the bug tracker:

#7475: codecs missing: base64 bz2 hex zlib ... -> reintroduce the codecs removed from Python3

#8838: Remove codecs.readbuffer_encode() -> remove the last part of the removed codecs

If I understood correctly, the question is: should codecs module only contain encoding codecs, or contain also other kind of codecs.

Encoding codec API is now strict (encode: str->bytes, decode: bytes->str), it's not possible to reuse str.encode() or bytes.decode() for the other codecs. Marc-Andre Lemburg proposed to add .tranform() and .untranform() methods to str, bytes and bytearray types. If I understood correctly, it would look like:

b'abc'.transform("hex") '616263' '616263'.untranform("hex") b'abc'

I suppose that each codec will have a different list of accepted input and output types. Example:

bz2: encode:bytes->bytes, decode:bytes->bytes rot13: encode:str->str, decode:str->str hex: encode:bytes->str, decode: str->bytes

And so "abc".encode("bz2") would raise a TypeError.

--

In my opinion, we should not mix codecs of different kinds (compression, cipher, etc.) because the input and output types are different. It would have more sense to create a standard API for each kind of codec. Existing examples of standard APIs in Python: hashlib, shutil.make_archive(), database API, etc.

-- Victor Stinner http://www.haypocalc.com/

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