PHP Sadness

(<5.6) Occasionally significant parentheses

There are cases where simply wrapping code in parentheses changes the result. For example, consider a function r() which returns a reference to its argument:

// r() simply returns a reference to a given variable.
function &r(&$v){return $v;}


// Here, we have a scalar $a on which settype() fails to operate if
// parentheses are involved.
print "Scalar demonstration:\n";
$a = 1;

// First with parentheses, then without.
//       v       v
settype( ( r($a) ) , "boolean"); var_dump($a);
settype(   r($a)   , "boolean"); var_dump($a);
//       ^       ^


// Here is a similar situation where array_pop() fails to operate upon a
// reference to an array if parentheses are involved.
print "\nArray demonstration:\n";
$b = array("c");

// First with parentheses, then without.
//         v       v
array_pop( ( r($b) ) ); print_r($b);
array_pop(   r($b)   ); print_r($b);
//         ^       ^

Note how, in both demonstrations, the first invocation has no effect:

Scalar demonstration:
int(1)
bool(true)

Array demonstration:
Array
(
    [0] => c
)
Array
(
)

Apparently, references are so fragile (read: such a special case in the parser) that even parentheses force them back into plain values.

(E_STRICT will emit a warning here; that still does not make this behavior okay. "Strict Standards: Only variables should be passed by reference ...")