[Python-Dev] join()

Ka-Ping Yee ping at lfw.org
Sat Jun 12 10:12:38 CEST 1999

On Fri, 11 Jun 1999, Skip Montanaro wrote:
>     BAW> The only reason for making it a builtin would be to avoid pulling
>     BAW> in all of string just to get join.
> I still don't understand the motivation for making it a builtin instead of a
> method of the types it operates on.  Making it a builtin seems very
> un-object-oriented to me.

Builtin-hood makes it possible for one method to apply to
many types (or a heterogeneous list of things).

I think i'd support the

    def join(list, sep=None):
        if sep is None:
            result = list[0]
            for item in list[1:]:
                result = result + item
            result = list[0]
            for item in list[1:]:
                result = result + sep + item

idea, basically a reduce(operator.add...) with an optional
separator -- *except* my main issue would be to make sure that
the actual implementation optimizes the case of joining a
list of strings.  string.join() currently seems like the last
refuge for those wanting to avoid O(n^2) time when assembling
many small pieces in string buffers, and i don't want it to
see it go away.


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