How do I create a dictionary of functions in PHP?

Question

I want to have a dictionary of functions. With this dictionary, I could have a handler that accepts a function name and an array of arguments, and executes that function, returning the value it returns if it returns anything. The handler would throw an error if the name does not correspond to an existing function.

This would be very simple to implement Javascript:

var actions = {
  doSomething: function(){ /* ... */ },
  doAnotherThing: function() { /* ... */ }
};

function runAction (name, args) {
  if(typeof actions[name] !== "function") throw "Unrecognized function.";
  return actions[name].apply(null, args);
}

But since functions aren't really first class objects in PHP, I can't figure out how to do this easily. Is there a reasonably simple way to do this in PHP?

Answer 1

$actions = array(
    'doSomething'     => 'foobar',
    'doAnotherThing'  => array($obj, 'method'),
    'doSomethingElse' => function ($arg) { ... },
    ...
);

if (!is_callable($actions[$name])) {
    throw new Tantrum;
}

echo call_user_func_array($actions[$name], array($param1, $param2));

Your dictionary can consist of any of the allowable callable types.

Answer 2

I don't clearly get what you mean.
If you need an array of functions just do:

$actions = array(
'doSomething'=>function(){},
'doSomething2'=>function(){}
);

You can than run a function with $actions['doSomething']();

Of course you can have args:

$actions = array(
'doSomething'=>function($arg1){}
);


$actions['doSomething']('value1');

Answer 3

You could use PHP's __call() for that:

class Dictionary {
   static protected $actions = NULL;

   function __call($action, $args)
   {
       if (!isset(self::$actions))
           self::$actions = array(
            'foo'=>function(){ /* ... */ },
            'bar'=>function(){ /* ... */ }
           );

       if (array_key_exists($action, self::$actions))
          return call_user_func_array(self::$actions[$action], $args);
       // throw Exception
   }
}

// Allows for:
$dict = new Dictionary();
$dict->foo(1,2,3);

For static invocations, __callStatic() can be used (as of PHP5.3).

Answer 4

If You plan to use this in object context You do not have to create any function/method dictionary.

You can simply raise some error on unexisting method with magic method __call():

class MyObject {

    function __call($name, $params) {
        throw new Exception('Calling object method '.__CLASS__.'::'.$name.' that is not implemented');
    }

    function __callStatic($name, $params) { // as of PHP 5.3. <
        throw new Exception('Calling object static method '.__CLASS__.'::'.$name.' that is not implemented');
    }
}

Then every other class should extend Your MyObject class...

http://php.net/__call