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Date: Fri, 28 Nov 2014 16:27:53 +0400
Message-ID: <CA+9eiLviXr-MN-4sPTFiBBrFH-Hr8LajZKmELYzK+AhguZCWwA@mail.gmail.com>
To: Andrea Faulds <ajf@ajf.me>
Cc: Rowan Collins <rowan.collins@gmail.com>, Levi Morrison <levim@php.net>, 
	PHP Internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=047d7b33db6accb5250508ea63b5
Subject: Re: [PHP-DEV] [RFC][Discussion] Return Type Variance Checking
From: dmitry@zend.com (Dmitry Stogov)

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I didn't get what you mean.
parameters are invariant, "invariance, which is safe for both" and " it
shouldn't match parameters" are contradictory.

Thanks. Dmitry.

On Fri, Nov 28, 2014 at 1:57 PM, Andrea Faulds <ajf@ajf.me> wrote:

>
> > On 28 Nov 2014, at 09:31, Dmitry Stogov <dmitry@zend.com> wrote:
> >
> > I prefer option (3) - invariant return types.
> > Actually, return type compatibility check should follow all the rules for
> > parameter type compatibility check (may be even reuse or share the code).
>
> No, it shouldn't match parameters, that'd break type safety. What's safe
> for parameters is the opposite of what's safe for return types. The
> exception is invariance, which is safe for both.
>
> --
> Andrea Faulds
> http://ajf.me/

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