Helvensteijn.com

It’s no secret that PHP has some weird behaviors. I just ran into another one that I wasn’t aware of.

Functions in PHP can be defined after they are called, so long as they’re in the same file if memory serves me. The same doesn’t go for functions defined within other functions, though. Observe:

<?php

a();

function a() {
	b();
}

function b() {
	echo 'foo';
}

That does what you’d expect:

foo

If we now move b() into a(), like so:

<?php

a();

function a() {
	b();
	
	function b() {
		echo 'foo';
	}
}

Watch what happens:

Fatal error: Call to undefined function b() in <file> on line 6

Whereas this works again:

<?php

a();

function a() {
	function b() {
		echo 'foo';
	}

	b();
}

Ah well, we all knew PHP was inconsistent, what’s one more inconsistency?