Anywhere you are unconditionally including a class file, use
require_once
. Anywhere you are conditionally including a class file
(for example, factory methods), use include_once
. Either of these
will ensure that class files are included only once. They share the
same file list, so you don't need to worry about mixing them - a
file included with require_once
will not be included again by include_once
.
include_once
and require_once
are statements, not
functions. Parentheses should not surround the subject filename.
Example:
<?php require_once 'ClassExample1.php'; if (condition) { include_once 'ClassExample2.php'; } ?>