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

> > Guido van Rossum:
> OK, that's an example.  It's only so-so, because you should be using
> os.path.split() anyway.  It's done best as follows:
> 
>   temp, file = os.path.split(path)
>   main, parent = os.path.split(temp)

Greg Wilson:
Or "main, parent, file = os.path.split(path, -2)" :-)

> > Greg Wilson again:
> > Question still stands --- if these are counts, then shouldn't
> > negative values raise exceptions?
> 
> Given that it's documented with the name "maxsplit", it's not
> unreasonable that -1 is treated the same as 0.

Greg Wilson:
But it isn't:

>>> print sys.version
2.2a0 (#2, Apr 20 2001, 12:53:03)
[GCC 2.95.2 19991024 (release)]
>>> "abbc".replace("b", "x", 0)
'abbc'
>>> "abbc".replace("b", "x", -1)
'axxc'

Thanks,
Greg