[PHP-BUG] Req #68126 [NEW]: syntax for optional definition of function return type

From:             lefevre dot 10 at osu dot edu
Operating system: Linux
PHP version:      5.6.0
Package:          PHP Language Specification
Bug Type:         Feature/Change Request
Bug description:syntax for optional definition of function return type

Description:
------------
It would be useful to optionally be able define a return type for a
function, perhaps like so:

function foo($arg1, $arg2) returns array { ... }

Currently the Code by Contract principle is not fully implementable in
interfaces because there is no way to guarantee a return type for
functions, or even any return value at all. 

Adding a return type would allow one to do better code by contract:

interface iMyInterface {
  function handle_data($arg1) returns iMyResponse;
}
interface iMyResponse { ... } 

When writing code that implements or depends on iMyInterface, I can know
what type I will be getting out of the handle_data method.

Optionally one could specify multiple return types:

function my_string_function($string) returns string, boolean {...}

As the author of the function, I will know if I have a logic error when
this function I've written doesn't return the pre-defined types and I
get an error. 

As a client programer (who will later use the above function, but hasn't
written it), I will know at a glance what output I can expect from a
function, without scanning through the body to deduce it. 

For backwards compatibility, flexibility and php-ishness, I don't think
this should be required, but optional.

function my_string_function_1() {...}
function my_string_function_2() returns string, boolean {...}
function my_string_function_3() returns string, boolean, array {...}



Test script:
---------------
<?php

function my_string_function($string) returns array, string, boolean {
  // do nothing; syntax presently invalid.
}


-- 
Edit bug report at https://bugs.php.net/bug.php?id=68126&edit=1
-- 
Try a snapshot (PHP 5.4):   https://bugs.php.net/fix.php?id=68126&r=trysnapshot54
Try a snapshot (PHP 5.5):   https://bugs.php.net/fix.php?id=68126&r=trysnapshot55
Try a snapshot (trunk):     https://bugs.php.net/fix.php?id=68126&r=trysnapshottrunk
Fixed in SVN:               https://bugs.php.net/fix.php?id=68126&r=fixed
Fixed in release:           https://bugs.php.net/fix.php?id=68126&r=alreadyfixed
Need backtrace:             https://bugs.php.net/fix.php?id=68126&r=needtrace
Need Reproduce Script:      https://bugs.php.net/fix.php?id=68126&r=needscript
Try newer version:          https://bugs.php.net/fix.php?id=68126&r=oldversion
Not developer issue:        https://bugs.php.net/fix.php?id=68126&r=support
Expected behavior:          https://bugs.php.net/fix.php?id=68126&r=notwrong
Not enough info:            https://bugs.php.net/fix.php?id=68126&r=notenoughinfo
Submitted twice:            https://bugs.php.net/fix.php?id=68126&r=submittedtwice
register_globals:           https://bugs.php.net/fix.php?id=68126&r=globals
PHP 4 support discontinued: https://bugs.php.net/fix.php?id=68126&r=php4
Daylight Savings:           https://bugs.php.net/fix.php?id=68126&r=dst
IIS Stability:              https://bugs.php.net/fix.php?id=68126&r=isapi
Install GNU Sed:            https://bugs.php.net/fix.php?id=68126&r=gnused
Floating point limitations: https://bugs.php.net/fix.php?id=68126&r=float
No Zend Extensions:         https://bugs.php.net/fix.php?id=68126&r=nozend
MySQL Configuration Error:  https://bugs.php.net/fix.php?id=68126&r=mysqlcfg