====== PHP RFC: Stackable Error Handlers ======
  * Version: 0.1
  * Date: 2013-03-20
  * Author: Ferenc Kovács, tyra3l@gmail.com
  * Status: Draft
  * First Published at: https://wiki.php.net/rfc/stackable_error_handler

===== Introduction =====

This RFC tries to address the couple of feedback and possible shortcomings of the current error handler infrastructure, via introducing a stackable error handler infrastructure(similar to the current spl_autoload one), which can be used to extend or replace the default error handler using a stackable API where multiple error handlers can co-exist and only care about their own errors.

===== Proposal =====

There would be a built-in error handler set, which implements the current behavior:
- log the errors based on the config (error_reporting, log_error, error_log, etc.)
- display the errors based on the config.
- provides the $php_errormsg based on the config
- this handler is defined for E_ALL

When you call set_error_handler using the old signature the the error handler will replace/shadow any other error handler set via the old signature and they will always come after the built-in handler but before any handler added with the new stackable signature.
For example:
1. built-in E_ALL

set_error_handler(function($errno, $errstr, $errfile, $errline, $errcontext){/* do something here */}, E_WARNING)
1. built-in E_ALL
2. old-style E_WARNING

set_error_handler(function($errno, $errstr, $errfile, $errline, $errcontext){/* do something else here */}, E_NOTICE)
1. built-in E_ALL
2. old-style #2 E_NOTICE
 

The new stackable error handling would only generate and pass the error to the chain of handlers if there is at least one error handler set for that particular error type.


===== Backward Incompatible Changes =====

What breaks, and what is the justification for it?

===== Proposed PHP Version(s) =====

PHP 5.6 (or next major, if we happen to release a major version after 5.5).

===== SAPIs Impacted =====

TODO

===== New Constants =====

TODO

===== php.ini Defaults =====

TODO

===== Open Issues =====

TODO

===== Unaffected PHP Functionality =====

TODO

===== Future Scope =====

TODO

===== Proposed Voting Choices =====

TODO

===== Patches and Tests =====

TODO

===== References =====

TODO

===== Rejected Features =====

TODO