yield_all needed in Python

[Steven Bethard]

Terry Reedy wrote:
> "Steven Bethard" <steven.bethard at gmail.com> wrote in message 
> news:aNSdnYFA69ICiLjfRVn-ow at comcast.com...
>>
>>My suspicion is that if he doesn't like the * syntax when there's a close 
>>parallel to the argument parsing usage, he's not likely to like it when 
>>there isn't one.
> 
> Hmm.  My impression is that Guido did not like x,*y=iterable because he 
> does *not* see it as a 'close parallel' but as a strained analogy.  To me, 
> yield *iterable is closer to the use in function calling.  It would mean 
> 'unpack in time' rather than 'unpack in space' but that is natural (to me, 
> anyway) since that is what generators are about.

I don't see the * in
     yield *iterable
being much closer to the use in argument unpacking.  Note what happens 
to iterables after *:

py> def gen():
...     yield 1
...     yield 2
...     print "complete!"
...
py> def f(*args):
...     print args
...
py> f(*gen())
complete!
(1, 2)

The entire iterable is immediately exhausted.  So if
     yield *iterable
is supposed to parallel argument unpacking, I would expect that it would 
also immediately exhaust the iterable, e.g. it would be equivalent to:
     for item in tuple(iterable):
         yield item
which I don't think is what the OP wants.

I'm certain I could get used to the syntax.  I'm only suggesting that I 
don't find it very intuitive.  (And I *have* thought a lot about 
argument unpacking -- see my older threads about *args being an iterable 
instead of a tuple.)

STeVe