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Date: Fri, 17 Jan 2020 14:17:11 -0500
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To: Aran Reeks <cdtreeks@gmail.com>
Subject: Re: [PHP-DEV] Typed array properties V2
From: mike@newclarity.net (Mike Schinkel)


> On Jan 17, 2020, at 2:50 AM, Aran Reeks <cdtreeks@gmail.com> wrote:
> That said, there's a common use case that keeps me going back to them =
which
> I think would be a good thing for PHP to try and solve as a language
> feature - better typing of arrays to type their properties.

I for one would be a big +1 for this, with caveats. =20

> IDEs like PHPStorm handle this structure already hence sticking to =
that as
> a starting point...
>=20
> @returns []int

As previously noted, I assume you meant int[]?

----

Having the ability to type array elements would cover ~90% of the cases =
where I cannot properly type parameters or return values in PHP 7.4.

The caveat is that it would seem that to check dynamically would be an =
expensive proposition such as when an array that was not typed is passed =
to or returned from a function or assigned to a variable of a declared =
type, e.g.

function foo( $myarray ): Foo[] {
	return $myarray;  // This would need to be dynamically checked, =
I think?
}

Of course we could limit this type of typing to only arrays that are =
already know to be typed, meaning this would always fail:

function bar( Foo[] $myarray ) {
	// Do whatever
}
function baz( $myarray ) {
	bar( $myarray );  // Fails here because $myarray not known to be =
Foo[] even when it is
}
baz( [ new Foo() ] );

Alternately we could have a global option that would do type checking or =
not for these type hints, so they could be dynamically checked for all =
code prior to production code, where checking could be turned off.

Another option could be if the number of array elements is small (<100?) =
it could check, but otherwise not check, but this feels all kind of =
different types of wrong.

----

My vote, if I had one, would be to add type new typing for array =
elements, but also add a type checking global option that can be in one =
of 3 states:=20

1. Static checks only,=20
2. Dynamic checks only, or=20
3. No checking of array elements.

#jmtcw

-Mike
P.S. Or maybe there is an inexpensive way to keep track of the types of =
the entire array on element assignment?
P.P.S. Can someone please explain and give an example of how generics =
would make this need moot?  I do not get why that would be the case...