[Python-Dev] bytes type discussion (original) (raw)

"Martin v. Löwis" martin at v.loewis.de
Wed Feb 15 01:45:39 CET 2006

Bob Ippolito wrote:

Martin von Loewis's alternative for the "very controversial" set is to disallow an encoding argument and (I believe) also to disallow Unicode arguments. In 3.0 this would leave us with s.encode() as the only way to convert a string (which is always unicode) to bytes. The problem with this is that there's no code that works in both 2.x and 3.0.

Given a base64 or hex string, how do you get a bytes object out of it? Currently str.decode('base64') and str.decode('hex') are good solutions to this... but you get a str object back.

If s is a base64 string,

bytes(s.decode("base64"))

should work. In 2.x, it returns a str, which is then copied into bytes; in 3.x, .decode("base64") returns a byte string already (*), for which an extra copy is made.

I would prefer to see base64.decodestring to return bytes, though - perhaps even in 2.x already.

Regards, Martin

(*) Interestingly enough, the "base64" encoding will work reversed in terms of types, compared to all other encodings. Where .encode returns bytes normally, it will return a string for base64, and vice versa (assuming the bytes type has .decode/.encode methods).

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