Question

I have realized my module system by forcing modules to implement an abstract class, which contains mandatory methods which will be called by the base application. Now I want to realize a configuration form for each module. I thought about returning the type of the form as a property of my module skeleton class:

public abstract class Module
{
    public abstract Type ConfigurationForm { get; }
}

When displaying the configuration form, I simply instantiate a Form of this type and call the Show() method.

The problem is, I want to force the module to return a Type which is a sub class of System.Windows.Forms.Form, as the call would fail otherwise. What is the correct way to enforce this?

I thought about encapsulating the ConfigurationForm property in another property, which checks if it is inherited from Form, but I don’t think this is a clean way to accomplish this.

Answer 1

You could accomplish this with a generic type parameter

public abstract class Module<F> where F : Form
{
    public Type ConfigurationForm { get { return typeof(F); } }
}

But really this might make more sense:

public abstract class Module
{
    public abstract Form CreateConfigurationForm();
}

Edit: The advantage of using the 2nd option is that you can write code to work with your Module class without having to know specifically which kind of module you are dealing with