Extension:PhpTags Functions/Functions/Function handling

List of implemented functions

 * get_defined_functions — Returns an array of all defined functions
 * function_exists — Return TRUE if the given function has been defined

Waiting for implementation
This functions can be added by request
 * func_get_arg — Return an item from the argument list
 * func_get_args — Returns an array comprising a function's argument list
 * func_num_args — Returns the number of arguments passed to the function

This functions will be added after the implementation of the callback function in Runtime of Extension PhpTags.
 * call_user_func_array — Call a callback with an array of parameters
 * call_user_func — Call the callback given by the first parameter
 * create_function — Create an anonymous (lambda-style) function
 * forward_static_call_array — Call a static method and pass the arguments as array
 * forward_static_call — Call a static method
 * register_shutdown_function — Register a function for execution on shutdown
 * register_tick_function — Register a function for execution on each tick
 * unregister_tick_function — De-register a function for execution on each tick