Dependency Injection vs Service Location

Question

I am currently weighing up the advantages and disadvantages between DI and SL. However, I have found myself in the following catch 22 which implies that I should just use SL

Answer 1

I know this question is a little old, I just thought I would give my input.

In reality, 9 times out of 10 you really don't need SL and should rely on DI. However, there are some cases where you should use SL. One area that I find myself using SL (or a variation, thereof) is in game development.

Another advantage of SL (in my opinion) is the ability to pass around internal classes.

Below is an example:

internal sealed class SomeClass : ISomeClass
{
    internal SomeClass()
    {
        // Add the service to the locator
        ServiceLocator.Instance.AddService(this);
    }

    // Maybe remove of service within finalizer or dispose method if needed.

    internal void SomeMethod()
    {
        Console.WriteLine("The user of my library doesn't know I'm doing this, let's keep it a secret");
    }
}

public sealed class SomeOtherClass
{
    private ISomeClass someClass;

    public SomeOtherClass()
    {
        // Get the service and call a method
        someClass = ServiceLocator.Instance.GetService();
        someClass.SomeMethod();
    }
}

As you can see, the user of the library has no idea this method was called, because we didn't DI, not that we'd be able to anyways.