Question

I’d like to have a little php module. This module would have methods that are pure functions. So, this is just a collection of functions. All function get some arguments and return result depending only on input parameters.

I have some suggestions:

1. Static class

PHP hasn’t real static class, so I just make a class with all static methods:

class Some_Module
{
    static public function sum($a, $b, $c)
    {
        return $a+$b+$c;
    }

    static public function method2($a, $b)
    {
         return $a-$b+5;
    }
}

It’s very easy to use such modules:

$x = Some_module::sum(1,2,3);

But, I’ve heard (there are lots of topics on SO), that static is a bad practice.

2. Singleton

It’s not so easy to use:

// we should not to forget to get instance
$module_instance = new Some_module;
$x = $module_instance->sum(1,2,3);

Inconvenience is in that fact, that we should initialize this module now.
Also, there is a huge amount of topics on SO, where is explained why Singleton are not useful in PHP, so it’s a bad practice too.

What pattern to use for such a module?

Answer 1

I think this discussion will help in your decision Static methods: are they still bad considering PHP 5.3 late static binding?

Personally, it depends on the context. To store a bunch of misc. helper methods, more likely I’ll use it as a global and namespace it. In storing a limited amount of methods of a particular category that have no need to be instantiated, a static class might be a good option. Just be aware for unit testing purposes, many classes using static methods in the wrong context like cool::method is going to be hell.

// keep it abstract to prevent it from being instantiated
abstract class Foo {
   // cannot be altered if inherited, although limitation still exists
   final public static function bar() {
      echo 'test';
   }
}

Foo::bar();