====== Error Handling ======
Normally, when an error occurs in a PHP script, the error message is inserted into the script's output.  If the error is fatal, the script execution stops.


===== Production Server Configuration =====
Make sure to modify the php.ini file as shown below.  This will display a blank page without errors to the user if there is a problem.  You can enable logging to keep track of errors, which is done slightly below these lines.
  * Note:  Although display_errors may be set at runtime (with ini_set()), it won't have any affect if the script has fatal errors. This is because the desired runtime action does not get executed.
<code>
; Print out errors (as a part of the output).  For production web sites,
; you're strongly encouraged to turn this feature off, and use error logging
; instead (see below).  Keeping display_errors enabled on a production web site
; may reveal security information to end users, such as file paths on your Web
; server, your database schema or other information.
display_errors = Off

; Even when display_errors is on, errors that occur during PHP's startup
; sequence are not displayed.  It's strongly recommended to keep
; display_startup_errors off, except for when debugging.
display_startup_errors = Off
</code>

===== Changing Error Reporting =====
By default, all conditions except runtime notices are caught and displayed to the user.  You can change this behavior globally in your php.ini file with the error_reporting option.  You can also locally change the error-reporting behavior in a script using the error_reporting() function.

With both of these, you set the conditions that are caught and displayed by using the various bitwise operators for combinations.

Example - all error-level options:\\ 
(E_ERROR | E_PARSE | E_CORE_ERROR | E_COMPILE_ERROR | E_USER_ERROR)

Example - all options except runtime notices:\\ 
(E_ALL & ~E_NOTICE)

===== Error Reporting Values =====
^Value  ^Meaning  ^
|E_ERROR  |Runtime errors|
|E_WARNING  |Runtime warnings|
|E_PARSE  |Compile-time parse errors|
|E_NOTICE  |Runtime notices|
|E_CORE_ERROR  |Errors generated internally by PHP|
|E_CORE_WARNING  |Warnings generated internally by PHP|
|E_COMPILE_ERROR  |Errors generated internally by the Zend scripting engine|
|E_COMPILE_WARNING  |Warnings generated internally by the Zend scripting engine|
|E_USER_ERROR  |Runtime errors generated by a call to trigger_error()|
|E_USER_WARNING  |Runtime warnings generated by a call to trigger_error()|
|E_USER_NOTICE  |Runtime warnings generated by a call to trigger_error()|
|E_ALL  |All of the above options|

===== Error Suppression =====
  * disable error messages for a single expression:
    * $value = @(2 / 0);
  * turn off error reporting entirely:
    * error_reporting(0);

===== Triggering Errors =====
trigger_error(message [, type]);

* the second parameter is the condition level, which is either E_USER_ERROR, E_USER_WARNING, or E_USER_NOTICE (the default)

===== Defining Error Handlers =====
FIXME