[Python-Dev] bytes.from_hex() [Was: PEP 332 revival in coordination with pep 349?] (original) (raw)

M.-A. Lemburg mal at egenix.com
Sat Feb 18 12:06:37 CET 2006

Martin, v. Löwis wrote:

How are users confused? Users do py> "Martin v. Löwis".encode("utf-8") Traceback (most recent call last): File "", line 1, in ? UnicodeDecodeError: 'ascii' codec can't decode byte 0xf6 in position 11: ordinal not in range(128) because they want to convert the string "to Unicode", and they have found a text telling them that .encode("utf-8") is a reasonable method. What it should tell them is py> "Martin v. Löwis".encode("utf-8") Traceback (most recent call last): File "", line 1, in ? AttributeError: 'str' object has no attribute 'encode'

I've already explained why we have .encode() and .decode() methods on strings and Unicode many times. I've also explained the misunderstanding that can codecs only do Unicode-string conversions. And I've explained that the .encode() and .decode() method do check the return types of the codecs and only allow strings or Unicode on return (no lists, instances, tuples or anything else).

You seem to ignore this fact.

If we were to follow your idea, we should remove .encode() and .decode() altogether and refer users to the codecs.encode() and codecs.decode() function. However, I doubt that users will like this idea.

bytes.encode CAN only produce bytes. I don't understand MAL's design, but I believe in that design, bytes.encode could produce anything (say, a list). A codec can convert anything to anything else.

True. However, note that the .encode()/.decode() methods on strings and Unicode narrow down the possible return types. The corresponding .bytes methods should only allow bytes and Unicode.

-- Marc-Andre Lemburg eGenix.com

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