why do we use the code like "call_user_func($callback,$param)" insteed of "$callback($param)"

Question

PHP is just a scripting language,so we can do many things simple and efficient. Why not use the easy and simple way to do it like "$callback($param)" ?

Answer 1

not sure but I could think of that later one is simply a synonym for first one. so internally may php switches it.

Even if not I like the option to have both ways, because for someone not developing in PHP the later one may not be very intuitive but calling a function is quite similar in all languages.

EDIT: A nice reading about this can be found here ...