kay,
your suggestion makes perfect sense for me, i haven't actually tried
the examples tho. guess there could be a find() or index() or
indices() or iterIndices() ??? function 'f' roughly with these arguments:
def f( x, element, start = 0, stop = None, default = _Misfit, maxcount =
None, reverse = False )
that iterates over the indices of x where element (a substring, key, or
value in a sequence or iterator) is found, raising sth. like IndexError
when nothing at all is found except when default is not '_Misfit'
(mata-None),
and starts looking from the right end when reverse is True (this *may*
imply that reversed(x) is done on x where no better implementation is
available). not quite sure whether it makes sense to me to always return
default as the last value of the iteration -- i tend to say rather not.
ah yes, only up to maxcount indices are yielded.
bet it said that passing an iterator for x would mean that the iterator is
gone
up to where the last index was yielded; passing an iterator is not
acceptable for reverse = True.
MHO,
_wolf
On Sat, 27 Aug 2005 14:57:08 +0200, Kay Schluehr <[EMAIL PROTECTED]>
wrote:
>
> def keep(iter, default=None):
> try:
> return iter.next()
> except StopIteration:
> return default
>
> Together with an index iterator the user can mimic the behaviour he
> wants. Instead of a ValueError a StopIteration exception can hold as
> an "external" information ( other than a default value ):
>
> >>> keep( "abcdabc".index("bc"), default=-1) # current behaviour of the
> # find() function
> >>> (idx for idx in "abcdabc".rindex("bc")) # generator expression
>
>
> Since the find() method acts on a string literal it is not easy to
> replace it syntactically. But why not add functions that can be hooked
> into classes whose objects are represented by literals?
>
> def find( string, substring):
> return keep( string.index( substring), default=-1)
>
> str.register(find)
>
> >>> "abcdabc".find("bc")
> 1
>
> Now find() can be stored in a pure Python module without maintaining it
> on interpreter level ( same as with reduce, map and filter ).
>
> Kay
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