Word for a non-iterator iterable?

[Leif K-Brooks]

Is there a word for an iterable object which isn't also an iterator, and
therefor can be iterated over multiple times without being exhausted?
"Sequence" is close, but a non-iterator iterable could technically
provide an __iter__ method without implementing the sequence protocol,
so it's not quite right.

[vincent wehren]

Re: Word for a non-iterator iterable?

Leif K-Brooks wrote:[color=blue]
> Is there a word for an iterable object which isn't also an iterator, and
> therefor can be iterated over multiple times without being exhausted?
> "Sequence" is close, but a non-iterator iterable could technically
> provide an __iter__ method without implementing the sequence protocol,
> so it's not quite right.[/color]

How about 'reiterable'?

--
Vincent Wehren

[Alex Martelli]

Re: Word for a non-iterator iterable?

Leif K-Brooks <eurleif@ecritt ers.biz> wrote:
[color=blue]
> Is there a word for an iterable object which isn't also an iterator, and
> therefor can be iterated over multiple times without being exhausted?
> "Sequence" is close, but a non-iterator iterable could technically
> provide an __iter__ method without implementing the sequence protocol,
> so it's not quite right.[/color]

Not just ``technically'' -- a dict is a good and very common example of
just such a "non-iterator, non-sequence iterable".

As you're focusing on "can be iterated over multiple-times", I like
"re-iterable"; it centers on what you can DO with the object, rather
than quibbling what it ISN'T;-)


Alex

[Terry Reedy]

Re: Word for a non-iterator iterable?


"vincent wehren" <vincent@visual trans.de> wrote in message
news:cu4kjo$d8s $1@news2.tilbu1 .nb.home.nl...[color=blue]
> Leif K-Brooks wrote:[color=green]
>> Is there a word for an iterable object which isn't also an iterator, and
>> therefor can be iterated over multiple times without being exhausted?[/color][/color]

The 'therefor' above is a non sequitor. A non-iterator iterable can also
be non-reiterable.
[color=blue]
> How about 'reiterable'?[/color]

I agree. Reiterability is essential for some algorithms, while I am hard
put to think of a situation in which non-iterator-ness, by itself, is.

Terry J. Reedy

[Oren Tirosh]

Re: Word for a non-iterator iterable?

Leif K-Brooks <eurleif@ecritt ers.biz> wrote in message news:<36lu1cF51 6qtdU1@individu al.net>...[color=blue]
> Is there a word for an iterable object which isn't also an iterator, and
> therefor can be iterated over multiple times without being exhausted?
> "Sequence" is close, but a non-iterator iterable could technically
> provide an __iter__ method without implementing the sequence protocol,
> so it's not quite right.[/color]

"reiterable ". I think I was the first to use this word on
comp.lang.pytho n.

If you have code that requires this property might want to use this
function:

..def reiter(x):
.. i = iter(x)
.. if i is x:
.. raise TypeError, "Object is not re-iterable"
.. return i

example:

..for outer in x:
.. for inner in reiter(y):
.. do_something_wi th(outer, inner)

This will raise an exception when an iterator is used for y instead of
silently failing after the first time through the outer loop and
making it look like an empty container.

When iter() returns a new iterator object it is a good hint but not a
100% guarantee that the object is reiterable. For example, python 2.2
returned a new xreadlines object for iterating over a file but it
messed up the underlying file object's state so it still wasn't
reiterable. But when iter() returns the same object - well, that's a
sign that the object is definitely not reiterable.

Oren

[Terry Reedy]

Re: Word for a non-iterator iterable?


"Oren Tirosh" <oren@REMOVETHI S1.hishome.net> wrote in message
news:cf052f0d.0 502071110.4e961 1e0@posting.goo gle.com...[color=blue]
> But when iter() returns the same object - well, that's a
> sign that the object is definitely not reiterable.[/color]

Unless, of course, __iter__ resets the iteration variable to its starting
value. But it would definitely not be simultaneously doubly iterable, as
one would want to compute a self crossproduct. And one could object that
such an __iter__ is not proper for an iterator (return self and do nothing
else). So such an __iter__ should better be written, perhap as a generator
function, to return an independent object with independently initialized
iteration variable.

Terry J. Reedy