CODEWITHSUNDEEP
c#winformsproperties
Xavi Anguera
Xavi Anguera

Reputation: 105

How to define a property that has a type as a value

I want to define a property (named FormAbout) in a class, so that someone using this object could assign a derived type of IFormAbout. To do this, I have an interface and an implementation of it:

public interface IFormAbout : IDisposable
{
    void ShowAbout();
}

public partial class MyFormAbout : Form, IFormAbout
{
    public void ShowAbout()
    {
        base.ShowDialog();
        // ...
    }

    // ...
}

Here, the main Form with the property I'd like to define:

public partial class FormMain : Form
{
    // --- This is what I don't know how to do --- //
    public Type<IFormAbout> FormAbout { get; set; }
    // ------------------------------------------- //

    private void SomeMethod()
    {
        using (FormAbout frm = new FormAbout())
        {
            frm.ShowAbout();
            // ...
        }
    }
}

The property would be set somehow like this:

formMain1.FormAbout = typeof(MyFormAbout);

Is it possible to do? Thanks in advance.

Upvotes: 1

Views: 69

Answers (2)

Xavi Anguera
Xavi Anguera

Reputation: 105

Finally I've found a good solution to my question, and I want to share it with you all. It is possible to set an explicit implementation of IFormAbout without instantiate it, by declaring my class FormMain as generic:

public partial class FormMain<About> : Form where About : IFormAbout
{
    private void SomeMethod()
    {
        using (About frm = Activator.CreateInstance<About>())
        {
            frm.ShowAbout();
            // ...
        }

        // ...
    }
}

Then, we just have to declare an instance of FormMain like this:

FormMain<MyFormAbout> frm = new FormMain<MyFormAbout>();

Good enough for my purposes.

Upvotes: 0

MakePeaceGreatAgain
MakePeaceGreatAgain

Reputation: 37000

although you could have a property of type Type, that´s not what you want here. You just want to assign a new instance of MyFormAbout to the property, don´t you? So the type of the property becomes IFormAbout:

public partial class FormMain : Form
{
    public IFormAbout FormAbout { get; set; }

    private void SomeMethod()
    {           
        FormAbout.ShowAbout();
        // ...
    }
}

Now you do not need to assign a type, but a concrete instance of it:

FormMain1.AboutForm = new MyAboutForm();
formMain1.SomeMethod(); // this will use the aboutForm from above

Upvotes: 2

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