[Python-ideas] generator vs iterator etc. (was: How assignment should work with generators?)

Stephen J. Turnbull turnbull.stephen.fw at u.tsukuba.ac.jp
Tue Nov 28 01:11:25 EST 2017

Steven D'Aprano writes:

 > The subset of iterators which are created as generators are *also* 
 > called generators,

As long as we're being precise, I don't think that is precisely correct:

    >>> (x for x in range(1))
    <generator object <genexpr> at 0x10dee5e08>
    >>> iter(range(1))
    <range_iterator object at 0x10dab83f0>
    >>> iter((1,))
    <tuple_iterator object at 0x10df109b0>

The two iterators have the same duck-type, the generator is different.
A generator (object) is, of course, an interable.

 > You are right that sometimes the term "generator" is used as
 > shorthand for "generator function".

I've always thought "generator factory" would be a better term, but
"generator function" will do.  I generally use "generator object" to
make the distinction, though.

 > Most of the time the distinction doesn't actually matter, since you
 > cannot (easily?) create a generator without first creating a
 > generator function.

At least you can create a generator (object) with the generator
function created and called implicitly by using a generator

Reverting from pedantic mode.  Hear, hear! this:

 > Or if it does matter, it is clear in context which is meant.
 > For those few times where it *does* matter, there is no substitute for 
 > precision in language, and that depends on the author, not the 
 > terminology.


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