Asynchronous programming

[Jussi Piitulainen]

Michael Selik <michael.selik at gmail.com> writes:

> On Thu, Aug 11, 2016 at 11:46 AM Michael Selik <michael.selik at gmail.com>
> wrote:
>
>> On Thu, Aug 11, 2016 at 11:01 AM Steven D'Aprano <
>> steve+python at pearwood.info> wrote:
>>
>>> That ... looks wrong. You're taking something which looks like a procedure
>>> in the first case (trn.execute), so it probably returns None, and yielding
>>> over it. Even it that's not wrong, and it actually returned something
>>> which
>>> you ignored in the first case
>>>
>>
>> It's a standard, perhaps a mistaken standard, but nonetheless database
>> cursors tend to have that feature: execute returns the mutated self. I
>> agree that execute looks like it should return None instead. The return
>> self pattern feels Rubyish to me (or Rubic?).
>>
>
> Contradicting myself:
>     yield from c.execute(query).fetchall()    # looks good
>     yield from c.execute(query)                   # looks bad

The first looks like it allocates a list to hold all the results at once
only to yield each result one by one.

How about:
    c.execute(query)
    yield from c