Request for Comments: How to write RFCs

• Version: 1.0
• Date: 2011-09-19
• Author: Etienne Kneuss colder@php.net
• Status: Under Discussion
• First Published at: http://wiki.php.net/rfc/prototype_checks

Past discussions on the mailing lists have shed some light on the various ways we handle prototype checks and what may be done to improve PHP in that area. This RFC summarizes the current state (5.3/5.4) of prototype checks and possible improvements to it

Prototype checks occur in different contexts:

The prototype is checked with current normal rules (see Current rules). Any mismatch with current rules generates a FATAL error.

The prototype is checked with current normal rules (see Current rules). Any mismatch with current rules generates a FATAL error.

The prototype is checked with current normal rules (see Current rules). Any mismatch with current rules generates a STRICT error.

Scenario:

abstract class ParentAbs {
    abstract public function foo($a);
}
abstract class SubAbs extends ParentAbs {
    abstract public function foo($a);
}

NOT allowed, always result in a fatal error even if the prototypes are compatible.

Scenario:

interface ParentIface {
    function foo($a);
}
interface SubIface extends ParentIface {
    function foo($a);
}

NOT allowed, always result in a fatal error even if the prototypes are compatible.

This part specifies what is currently considered as valid signature modifications:

function foo($a)

is compatible with, in a sub class:

function foo($a, $b = 42)

function foo($a)

is compatible with, in a sub class:

function &foo($a)

This part specifies what is currently considered as invalid signature modifications:

Given:

class A {}
class B extends A{}

function foo(A $a)

is imcompatible with, in a sub class:

function foo(B $a)

function &foo()

is imcompatible with, in a sub class:

function foo()

function foo()

is imcompatible with, in a sub class:

function foo($a)

This part specifies what is currently considered as invalid modifications, despite being theoretically sound:

function foo(Array $a)

is currently imcompatible with, in a sub class:

function foo($a)

Given:

class A {}
class B extends A{}

function foo(B $a)

is currently imcompatible with, in a sub class:

function foo(A $a)

function foo(&$a)

is currently imcompatible with, in a sub class:

function foo($a)

function foo($a)

is currently imcompatible with, in a sub class:

function foo()