How do I create a dynamic method in PHP?

I'm trying to extend my ActiveRecord class with some dynamic methods. I would like to be able to run this from my controller

$user = User::find_by_username(param);
$user = User::find_by_email(param);

I've read a little about overloading and think that's the key. I'v got a static $_attributes in my AR class and I get the table name 开发者_StackOverflow社区by pluralizing my model (User = users) in this case.

How do I do this? All models extends the ActiveRecord class.

You have to use the __callStatic() magic method, which is available as PHP5.3

public static function __callStatic($name, $arguments) {
/*
    Use strpos to see if $name begins with 'find_by'
    If so, use strstr to get everything after 'find_by_'
    call_user_func_array to regular find method with found part and $arguments
    return result
*/
}

This might also be of use, it's more complex, but it allows true dynamic functions with access to member variables.

class DynamicFunction {
    var $functionPointer;
    var $mv = "The Member Variable";

    function __construct() {
        $this->functionPointer = function($arg) {
            return sprintf("I am the default closure, argument is %s\n", $arg);
        };
    }

    function changeFunction($functionSource) {
        $functionSource = str_replace('$this', '$_this', $functionSource);
        $_this = clone $this;

        $f = '$this->functionPointer = function($arg) use ($_this) {' . PHP_EOL;
        $f.= $functionSource . PHP_EOL . "};";
        eval($f);
    }

    function __call($method, $args) {
        if ( $this->{$method} instanceof Closure ) {
            return call_user_func_array($this->{$method},$args);
        } else {
            throw new Exception("Invalid Function");
        }
    }
}

if (!empty($argc) && !strcmp(basename($argv[0]), basename(__FILE__))) {
    $dfstring1 = 'return sprintf("I am dynamic function 1, argument is %s, member variables is %s\n", $arg, $this->mv);';
    $dfstring2 = 'return sprintf("I am dynamic function 2, argument is %s, member variables is %s\n", $arg, $this->mv);';

    $df = new DynamicFunction();
    $df->changeFunction($dfstring1);
    echo $df->functionPointer("Rabbit");

    $df->changeFunction($dfstring2);
    $df->mv = "A different var";
    echo $df->functionPointer("Cow");
};