How does php execute a function assigned to variable?

Question

Ok, I didn't really know how to even phrase the question, but let me explain.

Suppose I have a variable:

$file = dirname(__FILE__);

What happens if I assign $file to another variable?

$anotherVariable = $file;

Does the dirname function get executed each time I assign?

Thanks for any help.

Answer 1

No. PHP is imperative, so the right hand side of assignment expressions is evaluated, and the result stored "in the" left hand side (in the simple and almost ubiquitous case, the variable named on the left hand side).

$a = $b;  // Find the value of $b, and copy it into the value of $a
$a = 5 + 2; // Evaulate 5 + 2 to get 7, and store this in $a
$a = funcName(); // Evaluate funcName, which is equivalent to executing the code and obtaining the return value. Copy this value into $a

This gets a little more complex when you assign by reference ($a = &$b), but we needn't worry about that for now.