[Python-Dev] [Fwd: In Python 2.6, bytes is str]

Brett Cannon brett at python.org
Mon Oct 6 08:55:12 CEST 2008

On Sun, Oct 5, 2008 at 11:43 PM, Steve Holden <steve at holdenweb.com> wrote:
> This does make it look rather as though bytes == str was a decision
> whose consequences weren't fully appreciated before implementation.

Well, you could say that about almost any change.

> Was this horror anticipated?

I didn't anticipate it.

> regards
>  Steve
> -------- Original Message --------
> Subject: In Python 2.6, bytes is str
> Date: Sun, 05 Oct 2008 22:30:17 -0700
> From: Bryan Olson <fakeaddress at nowhere.org>
> Organization: at&t http://my.att.net/
> To: python-list at python.org
> Newsgroups: gmane.comp.python.general
> Python 3 has the 'bytes' type, which the string type I've long wanted in
> various languages. Among other advantages, it is immutable, and
> therefore bytes objects can be dict keys. There's a mutable version too,
> called "bytearray".
> In Python 2.6, the name 'bytes' is defined, and bound to str. The 2.6
> assignment presents some pitfalls. Be aware.
> Consider constructing a bytes object as:
>    b = bytes([68, 255, 0])
> In Python 3.x, len(b) will be 3, which feels right.
> In Python 2.6, len(b) will be  12, because b is the str, '[68, 255, 0]'.
> I'm thinking I should just avoid using 'bytes' in Python 2.6. If there's
>  another Python release between 2.6 and 3.gold, I'd advocate removing
> the pre-defined 'bytes', or maybe defining it as something else.

I think it needs to be made clear that bytes is there for type
compatibility (e.g., ``isinstance(ob, bytes)``). And the bytes
literals work how you would expect.

What I would like to know if there are any other gotchas beyond the
constructor as all of the other uses act as you would expect.


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