Accessing properties of class through class interface

Question

Why can't I access the base class (testClass) properties through it's interface (ItestClass)? I have created the interface to avoid the actual Control (winforms/wpf) properties to be visible in the third class (newClass). if that is not possible is there a better way?

public class testClass : Control, ItestClass
{
    public int Property1 { set; get; }
    public int Property2 { set; get; }
    public testClass() { }
}
public interface ItestClass
{
    int Property1 { get; set; }
    int Property2 { get; set; }
}

public class newClass : ItestClass
{
    public newClass()
    {
        // Why are the following statements are not possible?
        Property1 = 1;
        // OR
        this.Property1 = 1;
    }
}

McGarnagle · Accepted Answer · 2014-04-25 16:09:21Z

5

The interface doesn't actually implement the properties -- you will still need to define them in the implementing class:

public class newClass : ItestClass
{
    int Property1 { get; set; }
    int Property2 { get; set; }

    // ...
}

Edit

C# doesn't support multiple inheritance, so you can't have testClass inherit both Control and another concrete class. You could always use composition instead, though. For example:

public interface ItestClassProps
{
    public ItestClass TestClassProps { get; set; }
}

public class testClass : Control, ItestClassProps
{
    public ItestClass TestClassProps { set; get; }

    public testClass() { }
}

edited Apr 25, 2014 at 16:09

answered Apr 25, 2014 at 15:48

McGarnagle

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10 Comments

D Stanley Over a year ago

@mason not in newClass.

Johnny Over a year ago

the thing is I simply didn't want to directly inherit testClass, as it would also show all the Control properties, instead I inherited it's interface to avoid that.

Johnny Over a year ago

so basically I need to redefine them in third class (newClass)?

McGarnagle Over a year ago

@Johnny yes, since C# doesn't support multiple inheritance, you have to use composition in this case.

McGarnagle Over a year ago

@Johnny so basically, either use encapsulation by passing a reference to "ItestClass" instead of "testClass", or use composition by giving "testClass" an "ItestClass" property (see my edit above).

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