Question

Does anyone here know when PHP executes include and include_once calls?

I’m wondering because I come from a Flash and Desktop development background where you have to import your classes at the beginning of each class.

But now that I am starting to build more complex PHP code, it seems like it would be better to just include classes when I actually need them to save on loading time. For example, look at the following psuedo code:

if (I_need_to_check_login)
 { 
   include_once "Class.class.php";
   $C = new Class();
 }

If I do this, is the file Class.class.php going to be included everytime the code is run or only when I execute the include_once.

I’m a bit of a Class freak and usually build a class for just about any functionality used by my apps, so I often have lots of class files.

Answer 1

Includes are only performed if interpreter ever gets there. eg:

$variable = false;
if ($variable) {
    include 'a.php';
} else {
    include 'b.php';
}

In this case only b.php would be included.

For more on its behavior: PHP Manual – include