[Python-3000] PEP 3137: Immutable Bytes and Mutable Buffer

[Jim Jewett]

On 9/26/07, Guido van Rossum <guido at python.org> wrote:

> Comparisons
> -----------

> The bytes and buffer types are comparable with each other and
> orderable, so that e.g. b'abc' == buffer(b'abc') < b'abd'.

I think bytes (regardless of length) should compare to integers, so that:

    b"" < -sys.maxint < 97 == b'a' < b'aa' < 98

(zero-length buffer < any integer; otherwise compare the number to the
first byte, and in case of ties, a BytesSequence of length 2 or more
is greater)

I'm not as sure about comparing to floats.

Should they be incomparable to integer sequences?

    (97, 98) != b'ab'
    not (97, 98) < b'ab'
    not (97, 98) > b'ab'


> Bytes and the Str Type
> ----------------------

> ... any attempt to mix bytes (or
> buffer) objects and str objects without specifying an encoding will
> raise a TypeError exception.  This is the case even for simply
> comparing a bytes or buffer object to a str object ...

Should a TypeError be raised as soon as you try to put a bytes and a
string in the same dict, even if they don't happen to hash equal?

(I assume that  buffer(b'abc') in {} will raise a TypeError, just as
list("abc") in {} would.)

> Therefore, support for the PEP 3118
> buffer API will be removed from the str type.

Good; this may be the single biggest aid for separting characters from
a particular (bytes) representation.

-jJ