Is '#IF DEBUG' deprecated in modern programming?

Question

This is my first StackOverflow question so be nice! :-)

I recently came across the following example in some C# source code:

public IFoo GetFooInstance()
{
    #IF DEBUG
        return new TestFoo();
    #ELSE
        return new Foo();
    #ENDIF
}

Which lead me to these questions:

1. Is the use of "#IF DEBUG" unofficially deprecated? If not what is considered to be a good implementation of its use?
2. Using a class factory and/or tools like MOQ, RhinoMocks, etc how could the above example be implemented?

Answer 1

Using an IoC container, the entire function becomes redundant, instead of calling GetFooInstance you'd have code similar to:

ObjectFactory.GetInstance<IFoo>();

The setup of your IoC container could be in code or through a configuration file.

Answer 2

Nope. We use it all the time to sprinkle diagnostic information in our assemblies. For example I have the following shortcut used when debugging:

#if DEBUG
        if( ??? ) System.Diagnostics.Debugger.Break();
#endif

Where I can change ??? to any relevant expresion like Name == "Popcorn". etc. This ensures that none of the debugging code leaks into the release build.