[Python-Dev] Iterable String Redux (aka String ABC)

[Georg Brandl]

Antoine Pitrou schrieb:
> (just my 2 eurocents)
> 
> Guido van Rossum <guido <at> python.org> writes:
>> 
>> I'm not against this, but so far I've not been able to come up with a
>> good set of methods to endow the String ABC with.
> 
> If we stay minimalistic we could consider that the three basic operations that
> define a string are:
> - testing for substring containment
> - splitting on a substring into a list of substrings
> - slicing in order to extract a substring

> Which gives us ['__contains__', 'split', '__getitem__'], and expands intuitively
> to ['__contains__', 'find', 'index', 'split', 'rsplit', '__getitem__'].

I'd argue that "find" is more primitive than "split" -- split is intuitively
implemented using find and slicing, but implementing find using split and
len is unintuitive.  (Of course, "index" can be used instead of "find".)

>> Another problem is
>> that not everybody draws the line in the same place -- how should
>> instances of bytes, bytearray, array.array, memoryview (buffer in 2.6)
>> be treated?
> 
> In the followup of the flatten() example, bytes and bytearray should be Strings,
> but array.array and memoryview shouldn't. array.array is really a different kind
> of container rather than a proper string, and as for memoryview... well, since
> it's not documented I don't know what it's supposed to do :-)

This is really a problem -- since the PEP 3118 authors don't seem
to bother, I'll have to write up something based on the PEP, but I
don't know if it is still up-to-date.

Georg