On Sat, Oct 30, 2021, 6:29 PM Chris Angelico <ros...@gmail.com> wrote:
> > At first I thought it might be harmless, but nothing I really care
> about. After the discussion, I think the PEP would be actively harmful to
> future Python features.
>
It's nothing more than an implementation detail. If you want to suggest -
> or better yet, write - an alternative implementation, I would welcome it.
> Can you explain how this is "actively harmful"?
>
Both the choice of syntax and the discussion of proposed implementation
(both yours and Steven's) would make it more difficult later to advocate
and implement a more general "deferred" mechanism in the future.
If you were proposing the form that MAL and I proposed (and a few others
basically agreed) of having a keyword like 'defer' that could, in concept,
only be initially available in function signatures but later be extended to
other contexts, I wouldn't see a harm. Maybe Steven's `@name=` could
accommodate that too.
I'm not sure what I think of a general statement like:
@do_later = fun1(data) + fun2(data)
I.e. we expect to evaluate the first class object `do_later` in some other
context, but only if requested within a program branch where `data` is in
scope.
The similarity to decorators feels wrong, even though I think it's probably
not ambiguous syntactically.
In a sense, the implementation doesn't matter as much if the syntax is
something that could be used more widely. Clearly, adding something to the
dunders of a function object isn't a general mechanism, but if behavior was
kept consistent, the underlying implementation could change in principle.
Still, the check for a sentinel in the first few lines of a function body
is easy and fairly obvious, as well as long-standing. New syntax for a
trivial use is just clutter and cognitive burden for learners and users.
>
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