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Date: Sun, 3 Feb 2019 17:51:32 -0200
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To: Rowan Collins <rowan.collins@gmail.com>
Cc: PHP Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Re: PHP 8: Method Overloading, The Ressurection
From: david.proweb@gmail.com (David Rodrigues)

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Em dom, 3 de fev de 2019 =C3=A0s 17:19, Rowan Collins <rowan.collins@gmail.=
com>
escreveu:

> On 03/02/2019 19:00, Christoph M. Becker wrote:
> > On 03.02.2019 at 19:39, David Rodrigues wrote:
> >
> >> overload function sum(int $a, int $b): int;
> >> overload function sum(float $b, float $b): float;
> > Which function would sum(17.4, 42) call?  Also consider:
> >
> >    sum(PHP_INT_MAX, PHP_INT_MAX)
> >
> > vs.
> >
> >    sum(PHP_INT_MAX+1, PHP_INT_MAX+1)
>
>
> Yes, marking overloaded functions explicitly definitely helps, but I
> think the dispatch part is more complex than it first seems. Classes and
> interfaces require a bit of subtlety too:
>
> class Foo {}
> class Bar extends Foo {}
>
> overload function foo(Foo $a, Foo $b);
> overload function foo(Foo $a, Bar $b);
> overload function foo(Bar $a, Foo $b);
>
> foo(new Bar, new Bar);
>

This example could be complex. So, what other languages does in cases like
that? Java, for instance.


>
> There are plenty of cases more complex than this, e.g. when a class
> implements multiple interfaces, and you need to find a matching signature=
.
>
> That's not to say it's impossible, just don't underestimate the edge
> cases you'll need to legislate for.
>
> Oh, and note that return types can't participate in overloading, because
> there's no concept of "desired type" to choose between them.
>

You are right, in general. But still is possible identify the desired type
if return is used as argument to a typed parameter, but I still thinks that
it could not be done in general terms, so maybe we should not includes
return type to overloading.


>
> Regards,
>
> --
> Rowan Collins
> [IMSoP]
>
>
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> PHP Internals - PHP Runtime Development Mailing List
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>
>

--=20
David Rodrigues

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