On Sat, Feb 8, 2020, at 17:14, Soni L. wrote:
> On 2020-02-08 6:53 p.m., Bruce Leban wrote:
> > On Sat, Feb 8, 2020 at 1:22 PM Chris Angelico <[email protected]> wrote:
> >> Exactly how much code would be wrapped in the 'with' block?
> >
> > This is an intriguing idea, and in the example it's fairly easy to wrap
> > the entire statement in the with block. It gets a bit more complicated with
> > short-circuit logic. This is a contrived example to make it easier to read:
> >
> >> result = (with alpha()) and ((with beta()) if (with gamma()) else (with
> >> delta()))
> >
> > needs to be interpreted something like:
(snip)
> > I don't think there's anything surprising there although precisely defining
> > the semantics will be a little tricky.
>
> I'd expect it to go more like
(snip)
My own expectation, for what it's worth, would be something like
try:
_alpha_set = _beta_set = _gamma_set = _delta_set = False
result = (_alpha_cm := alpha(), _alpha_set:=True)[0].__enter__() and
((same transform for beta) if (...gamma) else (...delta))
finally:
try:
if _delta_set: _delta_cm.__exit__()
finally:
try:
if _gamma_set: _gamma_cm.__exit__()
finally: ...
but this is more of a mess than I originally thought to define in scenarios
with multiple and/or conditionally-used context managers. It's also tempting to
try to define a way to, e.g. only include it in scope for the evaluation of the
condition in if statements and while loops.
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