[Patches] New builtin function repeat?

[Guido van Rossum]

> I made this module some time about but I still think it is neat.
> It creates a new function called repeat (I'm not stuck on the
> name).  You can use it like this:
> 
>     for line in repeat(sys.stdin.readline):
>         ...
> 
> The repeat function creates a new sequence object.  The function
> supplied is called for __getitem__.  By default, a false value
> returned from the function will raise an IndexError.  You can
> specifiy an alternate termination value.  For example:
> 
>     for line in repeat(sys.stdin.readline, ''):
>         ...
> 
> would work as well.
> 
> While I'm throwing out crazy ideas, how about adding some
> sequence methods to PyFileObject?  You could then do:
> 
>     file = open(...)
>     for line in file:
>         ...
> 
> Too weird?  Here is a patch and the module.

All Python 1.7 or Py3K material...  To be discussed on python-dev.

I expect to redesign the way for loops interact with sequences; there
will be a separate protocol, probably a method to extract a generator
from an arbitrary object, where the generator has first/next methods.
Then "for line in list" will create a list generator which keeps track
of the loop index, while "for line in file" will create a file
generator which leaves the state up to the file object.  Some b/w
compat issues arise.

--Guido van Rossum (home page: http://www.python.org/~guido/)