Question

$myVar=myFunction(array_reverse(explode('.', $_SERVER['SERVER_NAME'])));

Anything wrong with nesting functions like this?

Answer 1

This is ok as long as you can guarantee that each function will always return the desired type. For instance if a function might return a FALSE value, it may be cast to an unexpected value.

The example provided works because both explode (as called) and array_reverse will both always return an array.

A counter-example:

mysqli_query(mysqli_connect(...), 'INSERT INTO tbl VALUES ....');

Since mysqli_connect may return a resource OR FALSE it shouldn’t be chained like this. The return value should always be checked for correctness.