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Date: Thu, 6 Nov 2014 00:26:26 +0000
Cc: Dmitry Stogov <dmitry@zend.com>,
 Levi Morrison <morrison.levi@gmail.com>,
 internals <internals@lists.php.net>,
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To: Stas Malyshev <smalyshev@sugarcrm.com>
Subject: Re: [PHP-DEV] [RFC][Vote] Return Types
From: ajf@ajf.me (Andrea Faulds)


> On 5 Nov 2014, at 22:15, Stas Malyshev <smalyshev@sugarcrm.com> wrote:
>=20
> Hi!
>=20
>>    No, classes are not loaded for type checks, since it would be =
pointless
>>    - if the class is not loaded, you could not have a value of that =
type,
>>    so if the class is not present, the answer is "no".
>>=20
>>=20
>> It's not true anymore, with this proposal.
>=20
> This is not good. The base premise of type checks always was if you
> don't use them, they are basically free - you don't load the classes,
> you don't do any work, until you actually need them, and by then your
> class is supposed to be already loaded, so again it's not costly. But =
if
> just declaring a type could trigger loading of code, this may
> significantly increase the footprint and loading time for classes that
> have many options but only use some of them at the time.

It shouldn=E2=80=99t need to load any code normally, it=E2=80=99s only =
if an inheriting class changes the type.

> Also, it is kind of weird that arguments require exact match but =
return
> types do not. Not that we care for consistency anymore=E2=80=A6

Yeah, we should probably have arguments be contravariant or covariant.

I was going to argue that covariance is important, but now that I think =
about it, the most important case is just self. If I can have Foo::foo() =
return a Foo and Bar::foo() return a Bar, with Bar inheriting from Foo, =
and this not breaking the invariant type check, I=E2=80=99m happy.

--
Andrea Faulds
http://ajf.me/