Question

Let’s say I have something like this:

<?php

namespace Twitter;

    class Twitter {

        function __construct()
        {
            $config = array ('api' => 'something', 'api_url' => 'something2');
        }

        // some code goes here

    }

    class TwitterConnection {

        function __construct()
        {
            $config = array ('api' => 'something', 'api_url' => 'something2');
        }

        // some code goes here

    }
?>

and so on – there will be more classes that uses $config variables.

Now, the question is: how can I define config only once, and make it accessible across all classes?

Thanks

Answer 1

There are a couple of different things in play here – config data storage, and config data representation and use.

For storage, as martswite commented above, you could have a config file. You could also have config data stored in a database.

For data representation, you could have an array, like you’ve shown in your question, or a separate full-fledged object.

Usually, if you have objects that have a dependency on certain data in order to work, you pass (inject) that dependency into the object through its constructor. So, roughly, something like this:

class Example
{
    private $dependency;

    public function __construct($dependency)
    {
        $this->dependency = $dependency;
    }

    public function doSomething()
    {
        // do something with $this->dependency
    }
}

This would be tedious to do manually if you had many objects which required the same dependency. Thankfully, there are dependency injection containers which automate a lot of the process. Where do you find these containers? A Google search should yield results. That said, Symfony seems like a popular option: http://components.symfony-project.org/dependency-injection/

All that said, there’s a bit of a learning curve to understanding and using a DI container. Still, it’s probably the best way to go without introducing globals into your code.

Finally, just to give you an idea of how to use it, here’s some pseudo-code:

// Load config data from file/db/some other source.  Use it to populate an object (most likely) or array

// Set up the DI container to automatically inject the config data into the objects which require it

// Profit