[Python-Dev] Re: adding a bytes sequence type to Python

[M.-A. Lemburg]

Roman Suzi wrote:
> On Tue, 17 Aug 2004, M.-A. Lemburg wrote:
> 
> 
>>Michael Hudson wrote:
>>
>>>Anthony Baxter <anthony at interlink.com.au> writes:
>>>
>>>>A big +1 for a bytes() type, though. I'm not sure on the details,
>>>>but it'd be nice if it was possible to pass a bytes() object to,
>>>>for instance, write() directly.
>>>
>>>If bytes() doesn't implement the read buffer interface, someone
>>>somewhere is going to need shooting :-)
>>
>>Is there any reason you cannot use buffer() ?!
> 
> Is it mutable?
> My guess: no:

The buffer object itself can be read-only or read-write.
Unfortunately, the buffer() built-in always returns
read-only buffers. At C level it is easy to create a buffer
object from a read-write capable object.

>>>>d = u'123124'
>>>>ddd[0]
> 
> '1'
> 
>>>>ddd[1]
> 
> '\x00'
> 
>>>>ddd[1] = '1'
> 
> Traceback (most recent call last):
>   File "<stdin>", line 1, in ?
> TypeError: buffer is read-only
> 
> 
>>It already implements all the necessary things and has been
>>available for many years.
> 
> 
> It was in the shadows because we had byte-strings.

Right, so why not revive it ?!

Anyway, this whole discussion about a new bytes type doesn't
really solve the problem that the b'...' literal was
intended for: that of having a nice way to define (read-only)
8-bit binary string literals.

We already have a number of read-write types for storing binary
data, e.g. arrays, cStringIO and buffers. Inventing yet another
way to spell binary data won't make life easier.

However, what will be missing is a nice way to spell read-only
binary data.

Since 'tada' will return a Unicode object in Py3k, I think we
should reuse the existing 8-bit string object under the new
literal constructor b'tada\x00' (and apply the same source code
encoding semantics we apply today for 'tada\x00').

-- 
Marc-Andre Lemburg
eGenix.com

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