Check if value isset and null

Question

I need to check if value is defined as anything, including null. isset treats null values as undefined and returns false. Take the following as an

Answer 1

See Best way to test for a variable's existence in PHP; isset() is clearly broken

 if( array_key_exists('foo', $GLOBALS) && is_null($foo)) // true & true => true
 if( array_key_exists('bar', $GLOBALS) && is_null($bar)) // false &  => false