Cannot add custom function inside invoice_items.php

[RhymeGuy]

Hi,

Why its not possible to add function inside invoice_items.php?

For example (just an example) if I have function like:

Code Select Expand

function myFunction($a, $b, $c) {
//do something like
$sum = $a + $b + $c;
}
and if I add it to the invoice_items.php (or mail_html.php), the it will cause the problems when I want to change order status (I noticed that it will also cause errors when ordering). myFunction can be anything, even simple echo 'Hello world.';