On Tue, Jun 21, 2022 at 5:53 PM Brendan Barnwell <brenb...@brenbarn.net>
wrote:
> > In the example, we assume that the built-in function `type()` is special
> > in not counting as a reference to the binding for purpose of realizing a
> > computation. Alternately, some new special function like `isdeferred()`
> might be used to
> > check for ``Deferred`` objects.
>
> I'll have to ponder my thoughts about the proposal as a whole, but this
> particular aspect seems dubious to me. As I understand it this would
> require some fairly deep changes to how evaluation works in Python.
> Right now in an expression like `type(blah)`, there isn't any way for
> the evaluation of `blah` to depend on the fact that it happens to occur
> as an argument to `type`.
I absolutely agree that this is a sore point in my first draft. I could
shift the magic from `type()` to `isdeferred()`, but that doesn't really
change anything for your examples. I suppose, that is, unless
`isdeferred()` becomes something other than a real function, but more like
some sort of macro. That doesn't make me happy either.
However, I *would* like to be able to answer the question "Is this object a
DeferredObject?" somehow. For example, I'd like some way to write code
similar to:
if isdeferred(expensive_result):
log.debug("The computationally expensive result is not worth
calculating here")
else:
log.debug(f"We already hit a path that needed the result, and it is
{expensive_result}")
Any thoughts on what might be the least ugly way to get that?
--
Keeping medicines from the bloodstreams of the sick; food
from the bellies of the hungry; books from the hands of the
uneducated; technology from the underdeveloped; and putting
advocates of freedom in prisons. Intellectual property is
to the 21st century what the slave trade was to the 16th.
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