[Python-ideas] startsin ?

[Paul Moore]

On 30 September 2011 16:30, Tarek Ziadé <ziade.tarek at gmail.com> wrote:
> Hey,
>
> not sure how people do this, or if I missed something obvious in the
> stdlib, but I often have this pattern:
>
> starts = ('a', 'b', 'c')
> somestring = 'acapulco'
>
> for start in starts:
>    if somestring.startswith(start):
>        print "yeah"
>
>
> So what about a startsin() method, that would iterate over a sequence:
>
> if somestring.startsin('a', 'b', 'c'):
>    print "yeah"

if any(somestring.startswith(s) for s in starts)
    print "yeah"

> Implementing it in C should be faster as well

Probably slightly, but how critical is speed here?

> same deal with .endswith I guess

A benefit of the any() recipe is that it generalises, so you don't
need to have endsin as well, (or whatever else people might think
of...)

But it is a common pattern, and there's also the case where you want
to know *which" pattern matched, which any can't do, so there may be
some mileage in this. But it might be simpler just to accept that
you've reached the point where a simple regex is the best answer. Yes,
now you have two problems, I know :-)

Paul.