[Python-Dev] re: string slicing and method consistency

[Greg Wilson]

> > Greg Wilson:
> > if "abbc"[-1] is "c", and if
> > "abbc".replace("b", "x", 1) is "axbc", then shouldn't
> > "abbc".replace("b", "x", -1) be "abxc" (i.e. negative
> > numbers replace the *last* occurrences of the value)?
> > Same argument for "split", etc.

> Guido van Rossum:
> Dubious hypergeneralization.

Greg Wilson:
Do you have an editor macro set up yet to generate that
phrase? :-)

> Guido van Rossum:
> The thing is that this parameter,
> called maxsplit, is not really an index -- it's a count.

Greg Wilson:
Understood; I'm asking whether changing its name and
interpretation (in a way that doesn't break any existing
code) would be worthwhile:

    >>> path = "/some/long/path/to/file.html"
    >>> main, parent, file = path.split("/", -2)
    >>> main
    "/some/long/path"
    >>> parent
    "to"
    >>> file
    "file.html"

> > Greg Wilson:
> > Turns out that "abbc".replace("b", "x", -1) is "axxc"
> > (i.e. negative arguments are ignored).  I would have
> > expected this to raise a ValueError, if anything.  Is
> > there a reason for this behavior?

Greg Wilson again:
Question still stands --- if these are counts, then shouldn't
negative values raise exceptions?

Thanks,
Greg