====== Request for Comments: Class casting to scalar ======
  * Version: 1.0
  * Date: 2008-11-24
  * Author: Mark Karpeles <mark.at.hell.ne.jp>
  * Status: Under Discussion
  * First Published at: http://wiki.php.net/rfc/class_casting_to_scalar

This RFC covers a way to cast classes to scalar values other than strings.

===== Introduction =====

Currently the Zend Engine provides some magic to methods in classes with defined names, for example <nowiki>__</nowiki>toString() is called when someone attempts to cast a class to a string.

The purpose of this RFC is to propose a way to allow casting to other scalar types (boolean, double, integer).

==== Why casting? ====

For the same reasons as <nowiki>__</nowiki>toString() exists, casting to other types might be needed. Feature requests have been submitted regarding this in the past.

===== Possible features/implementations =====

==== Interface or magic method? ====

Currently two possibilities exists:
  * Implementing a new magic method, for example <nowiki>__</nowiki>scalarValue() or <nowiki>__</nowiki>cast() in the Zend Engine.
  * Creating a new interface (for example ScalarAccess?) and force the presence of one function (scalarValue()?) which will return the scalar value for this class.

==== Pass requested type? ====

Concern has been raised over the fact of passing the requested value type as parameter to the function, as it could be used to disallow some kinds of cast.

===== Proposal and Patch =====

  * Patch for <nowiki>__</nowiki>cast() against PHP 5.2.6: http://ookoo.org/svn/snip/php-5.2.6_class_cast_func.patch
  * Patch for <nowiki>__</nowiki>cast() against PHP 5.3.0: http://ookoo.org/svn/snip/php-5.3.0alpha2_class_cast_func.patch
  * Extension for ScalarAccess interface for PHP 5.2.6: http://ookoo.org/svn/snip/phpcastable/

==== Rejected Features ====

  * None yet

==== Bugs ====

  * When used with math operators, it seems we *have* to cast to integer if not explictly requested in the code. TODO: find a way to force our way with a float value if needed

===== Changelog =====

2008-11-24: Initial draft