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Date: Tue, 11 Feb 2020 22:58:48 -0500
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To: Chase Peeler <chasepeeler@gmail.com>
Subject: Re: [PHP-DEV] [RFC]
From: mike@newclarity.net (Mike Schinkel)

> On Feb 11, 2020, at 9:51 AM, Chase Peeler <chasepeeler@gmail.com> =
wrote:
>=20
> Can anyone thing of a use-case where you would want a string name of a
> function and a callable would not be acceptable, besides possibly =
debugging
> code that said 'echo "I'm calling ".myfunction::function;'? Everything =
that
> I can think of that accepts a function name, also accepts a callable =
(e.g.
> array_map), but I could be forgetting something.
>=20
> If not, then I think it makes sense to return a callable. It might not =
be
> entirely consistent with the behavior of ::class, but, a class isn't
> entirely consistent with a method/function either, so I think there is =
some
> latitude for small differences.
>=20
> As for the ::func vs ::function. I think ::function is safer, since =
it's a
> reserved word. Otherwise you might run into issues with something like =
this:
>=20
> class foo {
>  const func =3D "bar";
> }
>=20
> function foo(){}
>=20
> echo foo::func;
>=20
> Probably not something that happens very often, but, I think the 4 =
extra
> characters to prevent it would be worth it.-------

Returning a _closure_ instead of a string would be providing a feature =
we _already_ have instead of one we do _not_ have.

If we had ::function returning a string we could use =
Closure::fromCallable() to get a closure.  Or today just use fn() =3D> =
myfunc().=20

But if ::function instead returned a closure then there still would be =
no way to extract the name of a function as a string from a symbol where =
PHP can throw a warning if it does not recognize the symbol, such as in =
the case of a typo.

Seems to me having a shorter syntax to get a closure is an orthogonal =
concern.=20

If we want a shorthand for closure we should create an additional syntax =
for it but still provide a way to extract a function's name as a string =
from its symbol since that is currently _not_ possible. Getting a =
closure from a function symbol currently _is_ possible.

Much better to provide  ::function to return the name of the function =
and ::closure get a closure that can call the function. =20

Or have  ::function to return the name of the function and provide a =
syntax something like ${myfunc} to return a closure, which has been =
suggested later in this thread.=20

Or best would be to add ::nameof for functions, method, classes, =
interfaces and traits and provide access to closures using either =
::closure or a new short syntax.

-Mike

P.S. A language I specialized in during the late 80's and early 90's =
called Clipper implemented closures with the following syntax:

- Without parameters:  {|| expr } equivalent to function(){ return expr; =
} and fn() =3D> expr;
- With parameters:  {|a,b| expr } equivalent to function(a,b){ return =
expr; } and fn(a,b) =3D> expr;

If we want a shorter syntax for function closures than fn() =3D> =
myfunc() maybe we consider {|| myfunc() } which would be more general =
purpose than only returning a closure for a function?