yield from () Was: Re: weirdness with list()

[Peter Otten]

On 01/03/2021 00:47, Alan Gauld via Python-list wrote:
> On 28/02/2021 00:17, Cameron Simpson wrote:
>
>> BUT... It also has a __iter__ value, which like any Box iterates over
>> the subboxes. For MDAT that is implemented like this:
>>
>>      def __iter__(self):
>>          yield from ()
>
> Sorry, a bit OT but I'm curious. I haven't seen
> this before:
>
> yield from ()
>
> What is it doing?
> What do the () represent in this context?

The 0-tuple ;)

yield from x

is syntactic sugar for

for item in x:
     yield item

Instead of () you can use any empty iterable.
If x is empty nothing is ever yielded.