Prakhar Goel,
> Doesn't this just punt on how CdefFunction works? Feels like we're
> back to AST re-writing.
Indeed, internally it rewrites the AST, of course. I think that's the
simplest way to implement it. But it doesn't mean the user that write
the compile-time code would have to be aware of the AST at all.
I mean, if you have a good use-case for it, then I'm ok with allowing
the compile-time code manipulating it. But I'd really prefer this not be
the main use of the compile-time execution feature.
Greg Ewing,
> On 26/02/21 3:21 pm, Celelibi wrote:
> > def twice(f):
> > fun = CdefFunction(... use f ...)
> > return fun
> >
> > foo = CdefFunction(...)
> > ast.append(AstCdefFunction("foo", twice(foo)))
> >
> > I think this might even be doable without having to even detect the
> > closure in cython. We'd just have to let python perform the name lookup.
>
> The cdef function created inside twice() is going to have
> to be some kind of closure, because it needs access at run
> time to the particular f that was passed to twice() at
> compile time.
Yes, conceptually it's a closure. But not implemented as one.
Since the object `fun` (whose type is CdefFunction) is *not* a function,
it is not a closure in the usual sens. It's just some python object
having a reference to another object.
The only new feature might be to declare at the top-level the functions
that are referenced by the CdefFunction object that reach the top-level.
In short, the apparent closures are resolved during the compile-time
execution.
As Prakhar Goel pointed out, the AST of `fun` would hold a reference to
the AST of `foo`. The compile-time execution of the `twice` example
would produce an AST similar to that we would get by parsing the
following code.
cdef _unique_name_for_original_foo(x):
# Something math-y
cdef foo(x):
return _unique_name_for_original_foo(2*x)
Honestly, I would love to make a prototype as think there's really no
major obstacle, yet many seem to think there is.
Unfortunately, I don't think I'll have enough time until at least
several weeks.
Best regards,
Celelibi
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