iter(callable, sentinel)

[Will McGugan]

Hi,

I've been using Python for years, but I recently encountered something
in the docs I wasnt familar with. That is, using two arguements for
iter(). Could someone elaborate on the docs and maybe show a typical use
case for it?


Thanks,

Will McGugan

 

[Simon Forman]

Hi,

I've been using Python for years, but I recently encountered something
in the docs I wasnt familar with. That is, using two arguements for
iter(). Could someone elaborate on the docs and maybe show a typical use
case for it?


Thanks,

Will McGugan

I just found out about that recently too.

help(iter) shows this:
Help on built-in function iter in module __builtin__:

iter(...)
iter(collection) -> iterator
iter(callable, sentinel) -> iterator

Get an iterator from an object. In the first form, the argument
must
supply its own iterator, or be a sequence.
In the second form, the callable is called until it returns the
sentinel.

 

[Simon Forman]

Hi,

I've been using Python for years, but I recently encountered something
in the docs I wasnt familar with. That is, using two arguements for
iter(). Could someone elaborate on the docs and maybe show a typical use
case for it?


Thanks,

Will McGugan

D'oh! You said *elaborate*... Sorry. Fredrik Lundh gives a great
example of it's use in this thread:
http://groups.google.ca/group/comp.lang.python/browse_frm/thread/b3ab8141c492bb21/e3f71597917afaa3

Peace,
~Simon

 

[Simon Forman]

Hi,

I've been using Python for years, but I recently encountered something
in the docs I wasnt familar with. That is, using two arguements for
iter(). Could someone elaborate on the docs and maybe show a typical use
case for it?


Thanks,

Will McGugan

Also, FWIW, GvR said this (parenthetically) about a week ago on the
Python-3000 list: "I also think that the two-argument form
iter(function, sentinel) is not very successful or useful and might be
dropped, but that's a separate issue."