Bytes indexing returns an int

[Steven D'Aprano]

Ethan Furman wrote:

> On 01/07/2014 07:19 AM, David Robinow wrote:
>>
>> Python 3 grudgingly allows the "abomination" of byte strings (is that
>> what they're called?)
> 
> No, that is *not* what they're called.  If you find any place in the
> Python3 docs that does call them bytestrings please submit a bug report.

The name of the class is "bytes", but what they represent *is* a string of
bytes, hence "byte-string". It's a standard computer science term for
distinguishing strings of text from strings of bytes.


> On 01/07/2014 08:12 AM, Steven D'Aprano wrote:
>> People trying to port these libraries from 2.7 to 3 run into this
>> problem, and it causes them grief. This little difference between bytes
>> in 2.7 and bytes in 3.x is a point of friction which makes porting
>> harder, and I'm trying to understand the reason for it.
> 
> If I recall correctly the way it was explained to me:
> 
> bytes (lists, arrays, etc.) is a container, and when a container is
> indexed you get whatever the container held.  If you slice the container
> you get a smaller container with the appropriate items.

(There's also a bytearray type, which is best considered as an array. Hence
the name.) Why decide that the bytes type is best considered as a list of
bytes rather than a string of bytes? It doesn't have any list methods, it
looks like a string and people use it as a string. As you have discovered,
it is an inconvenient annoyance that indexing returns an int instead of a
one-byte byte-string.

I think that, in hindsight, this was a major screw-up in Python 3.



> bytes (and bytearrays) are containers of ints, so indexing returns an int.
> One big problem with this whole scenario is
> that bytes then lies about what it contains.  (And I hate lies! [1])
> 
> Anyway, I believe that's the rationale behind the change.
> 
> --
> ~Ethan~
> 
> [1] http://www.quickmeme.com/meme/3ts325

-- 
Steven