[Python-Dev] pprint(iterator)

[Guido van Rossum]

On Tue, Jan 27, 2009 at 2:06 PM, Oleg Broytmann <phd at phd.pp.ru> wrote:
> On Tue, Jan 27, 2009 at 01:46:35PM -0800, Raymond Hettinger wrote:
>>    <enumerate object: 'A', 'B', 'C', 'D', 'E', 'F'>
>
>   I like the idea, and I prefer this formatting. Also bear in mind there
> are infinite generators, and there are iterators that cannot be reset. For
> infinite generators pprint() must have a parameter, say, 'max_items', and
> print <generator: 'A', 'B', 'C', 'D', 'E', 'F', ...>. The situation with
> iterators that cannot be reset should be documented.

This pretty much kills the proposal. Calling a "print" function like
pprint() should not have a side effect on the object being printed.
I'd be okay of pprint() special-cased the views returned by e.g.
dict.keys(), but if all we know is that the argument has a __next__
method, pprint() should *not* be calling that.

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