=== Description

Essentially, this is a simple wrapper operator to directly call any system and user-defined functions in template.

It does not concern me much if doing so is good idea or 'pfui' as someone said on the #ezpublish channel. Undoubtedly
care has to be taken to avoid security and caching problems, etc. But it makes life a lot easier for me because i
dont have to write unexisting text processing functions in template language and dont need to set up separate
extension to every small operator i need. It's a swiss army knife - you can cut your hand but noone is forcing you to :)

=== Usage

There are two operators:
wrap_php_func(string functionname, array parameters [, boolean return_output])
wrap_user_func(string functionname, array parameters [, boolean return_output])

Parameters:
functionname : name of called function (ex. ereg_replace)
parameters : array of parameters to pass to function (ex. array('sour', 'sweet', 'Grapes are sour.') )
return_output : If set true(), the OUTPUT from the called function is returned, not its return value.

Returns:
The return value of function you call. If return_output is set true(), the OUTPUT from the function is returned
instead. This can be used to embed external applications in your template.

Security:
Function names callable through operator must be explicitly listed in wrap_operator.ini , anything else is not
allowed. There is [PHPFunctions] section for enabling calling system functions through wrap_php_func and
[UserFunctions] for userdefined functions.

Calling internal php functions:
Example: you want to use ereg_replace php function.
1. add line to [PHPFunctions] section in wrap_operator.ini: "PermittedFunctionList[]=ereg_replace"
2. call it in your template: {wrap_php_func('ereg_replace', array('sour', 'sweet', 'Grapes are sour.'))}

Calling user defined functions:
wrap_user_func expects each user funtion to be defined in separate file:
extension/wrap_operator/userfunctions/{user function name}.php
It uses include_once to read it in, so be sure to use <?php ?> around code.

Example: suppose you want to use following silly function in template:
<?php
function silly_thing($who)
{
return($who . ' is silly!');
}
?>

To do this you:
1. save the function in file extension/wrap_operator/userfunctions/silly_thing.php
2. add line to [UserFunctions] section in wrap_operator.ini: "PermittedFunctionList[]=silly_thing"
3. call it in your template: {wrap_user_func('silly_thing', array('This function'))}

Having ability to call your php functions like this is a very nice feature i think, kind of simplified plugin system for
operators. No need to write whole extension for some simple function. Also functions you have written can be easily
shared by pasting them to forum and copying from there. So share yours :)

=== Problems and debugging
Turn on template debugging to see data that is passed to and from function and error messages. Look at examples.
Look at code. Scratch head. Log on to #ezpublish to bug author.

=== Thoughts

I am not sure exactly what datatypes can be passed to functions from template like this. Should work ok for
integers, strings and boolean i think. If you are more informed about ez internals, please comment.

Using wrap_user_func with return_output=true() should enable easy embedding of existing php applications in
templates, called through the user function. I have tested just simple test case but maybe someone can think of something
more useful and post specific instructions..

Comments and suggestions for improvement are very welcome. Either post on forum or talk to zurgutt on #ezpublish irc
channel on irc.freenode.net.