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reinaldorock at yahoo dot com dot br ¶

5 years ago


Using closure to encapsulate environment
<?php
    $fib = function($n) use(&$fib) {
        if($n == 0 || $n == 1) return 1;
        return $fib($n - 1) + $fib($n - 2);
    };

   echo $fib(2) . "\n"; // 2
   $lie = $fib;
   $fib = function(){die('error');};//rewrite $fib variable 
   echo $lie(5); // error   because $fib is referenced by closure

?>

Alternative Fibonacci implementation using a self called function like javascript to encapsulate references variables.

<?php
$fib = call_user_func(function(){
   
    $fib = function($n) use(&$fib) {
        if($n == 0 || $n == 1) return 1;
        return $fib($n - 1) + $fib($n - 2);
    };

    return $fib;
});

echo $fib(2) . "\n";//2
$ok = $fib;

$fib = function(){die('error')};//rewrite $fib variable but don't referenced $fib used by closure
echo $ok(5);//result ok 
?>

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