En Wed, 27 Feb 2008 23:18:14 -0200, Steven D'Aprano
<[EMAIL PROTECTED]> escribió:
> I think there is a good case for % taking an iterator. Here's an
> artificial example:
>
> def spam():
> while True: yield "spam"
>
> spam = spam()
>
> "%s eggs tomato and %s" % spam
> "%s %s bacon tomato %s and eggs" % spam
> "%s %s %s %s %s %s %s %s truffles and %s" % spam
>
> The iterator could be arbitrarily complex, but the important feature is
> that the % operator lazily demands values from it, taking only as few as
> it needs. If the iterator is exhausted early, it is an error.
The % operator has to know whether you want to convert the iterator
itself, or the items yielded. Currently it checks whether its argument is
a tuple, and takes its contents. "%s" % "hello" is a (very handy) shortcut
for "%s" % ("hello",). Consider the following:
py> L = ["hello", "world"]
py> print "%s" % L
['hello', 'world']
Your suggestion would make it behave like this:
py> print "%s" % L
'hello'
Then, if one wants to display the container itself and not the contained
items, one should wrap *every* list and every sequence/iterator/iterable
object into an one-element tuple. Currently this is only required for
tuples.
Changing the % operator this way isn't a good idea, but your suggestion
could be used in another string method/operator/library function.
--
Gabriel Genellina
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