Iterable objects and array type hinting?

Question

I have a lot of functions that either have type hinting for arrays or use is_array() to check the array-ness of a variable.

Now I\'m starting to use ob

Answer 1

I use a simple (and maybe a little hackish) way to test for "iterability".

function is_iterable($var) {
    set_error_handler(function ($errno, $errstr, $errfile, $errline, array $errcontext)
    {
        throw new \ErrorException($errstr, null, $errno, $errfile, $errline);
    });

    try {
        foreach ($var as $v) {
            break;
        }
    } catch (\ErrorException $e) {
        restore_error_handler();
        return false;
    }
    restore_error_handler();
    return true;
}

When you try to loop a non iterable variable, PHP throws a warning. By setting a custom error handler prior the attempt to iterate, you can transform an error into an exception thus enabling you to use a try/catch block. Afterwards you restore the previous error handler to not disrupt the program flow.

Here's a small test case (tested in PHP 5.3.15):

class Foo {
    public $a = 'one';
    public $b = 'two';
}

$foo = new Foo();
$bar = array('d','e','f');
$baz = 'string';
$bazinga = 1;
$boo = new StdClass();    

var_dump(is_iterable($foo)); //boolean true
var_dump(is_iterable($bar)); //boolean true
var_dump(is_iterable($baz)); //boolean false
var_dump(is_iterable($bazinga)); //bolean false
var_dump(is_iterable($boo)); //bolean true