| isChild | anchor |
|---|---|
true |
basic_concept |
We can demonstrate the concept with a simple, yet naive example.
Here we have a Database class that requires an adapter to speak to the database. We instantiate the adapter in the
constructor and create a hard dependency. This makes testing difficult and means the Database class is very tightly
coupled to the adapter.
{% highlight php %}
adapter = new MySqlAdapter; } } class MysqlAdapter {} {% endhighlight %} This code can be refactored to use Dependency Injection and therefore loosen the dependency. {% highlight php %} adapter = $adapter; } } class MysqlAdapter {} {% endhighlight %} Now we are giving the `Database` class its dependency rather than it creating it itself. We could even create a method that would accept an argument of the dependency and set it that way, or if the `$adapter` property was `public` we could set it directly.