Initialising a static variable in PHP

Question

Taken from the PHP manual:

Like any other PHP static variable, static properties may only be initialized using a literal or constant; expressions are no

Answer 1

Because an array is not a function.

While array(1,2) looks like you are calling a function that is called array, you are doing none of the sorts. You are just making an array, which is not a function call. it is closer to saying $a = 1.