Is there any benefit of using null first in PHP?

Question

Possible Duplicate:
Why do some experienced programmers write comparisons with the value before the variable?

Answer 1

It prevents you from accidentally assigning the value to a variable, especially when only using loose type comparison (==):

if (self::$_instance = NULL) { … } // WHOOPS!, self::$_instance is now NULL

This style of conditions is often called yoda conditions. Performance wise there is no difference, both statements are equivalent.