[Python-ideas] str.rreplace

[Joao S. O. Bueno]

On 28 January 2014 01:18, Ron Adam <ron3200 at gmail.com> wrote:
>
>
> On 01/24/2014 07:36 PM, Andrew Barnert wrote:
>>>>>>
>>>>>> While we're speculatively overgeneralizing, couldn't all of the
>>>>>> index/find/remove/replace/etc. methods take a negative n to
>>>>>> count from the end, making r variants unnecessary?
>>>>
>>>> Strings already provide rfind and rindex (they're just not part of
>>>> the general sequence API). Since strings are immutable, there's also
>>>> no call for an "remove".
>
>
>> I was responding to Serhiy's (probably facetious or devil's advocate)
>> suggestion that we should regularize the API: add rfind and rindex to
>> tuple (and presumably Sequence), and those plus rremove to list (and
>> presumably MutableSequence), and so on.
>>
>> My point was that if we're going to be that radical, we might as well
>> consider removing methods instead of adding them. Some of the find-like
>> methods already take negative indices; expanding that to all of the
>> index-based methods, and doing the equivalent to the count-based ones,
>> and adding a count or index to those that have neither, would mean all
>> of the "r" variants could go away.
>
>
>
> How about a keyword to specify which end to index from?  When used, it would
> disable negative indexing as well.  When not used the current behaviour with
> negative indexing would be the default.
>
>     direction=0            # The default with the current
>     (or not specified)     #    negative indexing allowed.
>
>     direction=1   # From first. Negative indexing disallowed.
>     direction=-1  # From last.  Negative indexing disallowed.
>
> (A shorter key word would be nice, but I can't think of any that is as
> clear.)


I've just picked the whole thread at once -
and I am a little surprised no one  suggested what looks obvious to me
(or maybe someone did, I went over the e-mails
rather quickly):

Why not simply to allow negative indexes to the count argument?

It is pretty much unambiguous, straightforward (hmm..actually, the
opposite of that) and Pythonistas are used to think of negative
indices as counting from the right. Moreover, the convention could be
used for index, remove and even overloaded for split, and other
methods as well.


  js
 -><-