[Python-ideas] + operator on generators

[Brendan Barnwell]

On 2017-06-28 09:16, Steven D'Aprano wrote:
> On Tue, Jun 27, 2017 at 01:53:37PM -0700, Mike Miller wrote:
>> >
>> >On 2017-06-25 20:23, Steven D'Aprano wrote:
>>> > >I have a counter-proposal: introduce the iterator chaining operator "&":
>>> > >
>>> > >     iterable & iterable --> itertools.chain(iterable, iterable)
>>> > >
>> >
>> >I like this suggestion.  Here's another color that might be less
>> >controversial:
>> >
>> >     iterable3 = iterable1.chain(iterable2)
> That requires every iterable class to add its own reimplementation of
> chain, or else it will surprisingly not be chainable -- or at least it
> *sometimes*  won't be chainable.
>
> chain(iterable1, iterable2) would be more acceptable. The reason why a
> function would be better here than a method is explained in the FAQ for
> why len() is a function.

	I still think a good middle ground would be to have such a function, 
but have the return type of that function be an iterator that provides a 
.chain method or (better) defines __add__ to allow adding it to other 
iterables.  Then a single call to "chain" (or whatever the global 
function was called) would be enough to give you a nice readable syntax 
if you later want to chain other iterables on.  This behavior would not 
need to be stipulated for any other kinds of iterators; "chain" would 
just be a function that converts any iterable into a nicely chainable 
one, similar to how pathlib.Path converts a string into a nicely 
manipulable Path object that allows various handy path operations.

-- 
Brendan Barnwell
"Do not follow where the path may lead.  Go, instead, where there is no 
path, and leave a trail."
    --author unknown