[Python-Dev] bytes.from_hex() (original) (raw)

Stephen J. Turnbull stephen at xemacs.org
Sun Feb 26 17:05:51 CET 2006

"Greg" == Greg Ewing <greg.ewing at canterbury.ac.nz> writes:

Greg> I think we need some concrete use cases to talk about if
Greg> we're to get any further with this. Do you have any such use
Greg> cases in mind?

I gave you one, MIME processing in email, and a concrete bug that is possible with the design you propose, but not in mine. You said, "the programmers need to try harder." If that's an acceptable answer, I have to concede it beats all any use case I can imagine.

I think it's your turn. Give me a use case where it matters practically that the output of the base64 codec be Python unicode characters rather than 8-bit ASCII characters.

I don't think you can. Everything you have written so far is based on defending your maintained assumption that because Python implements text processing via the unicode type, everything that is described as a "character" must be coerced to that type.

If you give up that assumption, you get

  1. an automatic reduction in base64.upcase() bugs because it's a type error, ie, binary objects are not text objects, no matter what their representation

  2. encouragement to programmer teams to carry along binary objects as opaque blobs until they're just about to put them on the wire, then let the wire protocol guy implement the conversion at that point

  3. efficiency for a very common case where ASCII octets are the wire representation

  4. efficient and clear implementation and documentation using the codec framework and API

I don't really see a downside, except for the occasional double conversion ASCII -> unicode -> UTF-16, as is allowed (but not mandated) in XML's use of base64. What downside do you see?

-- School of Systems and Information Engineering http://turnbull.sk.tsukuba.ac.jp University of Tsukuba Tennodai 1-1-1 Tsukuba 305-8573 JAPAN Ask not how you can "do" free software business; ask what your business can "do for" free software.

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