Mutiple inheritance of Interfaces in Blazor razor file

Question

I have Blazor component that has only a razor file (without razor.cs code behind) and want the component to be inherited from an interface, first I tried the following :

MyComponent.razor :

  @inherits IMyInterface

Then after build I got an error in the .cs generated code(by Visual Studio) and I realized the component is only derived form my interface and not ComponentBase class. Here is the generated code:

...
public partial class MyComponent: IMyInterface
    {
        #pragma warning disable 1998
        protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder __builder)
        {
        }
        #pragma warning restore 1998
    }
...

so I got the 'no suitable method found to override' error.

then I tried the following codes and got a compile error with all of them :

// 1) multiple inheritance
@inherits ComponentBase,IMyInterface

// 2) adding semicolon 
@inherits ComponentBase,IMyInterface;

// 3) mutiple @inherits directive
@inherits ComponentBase
@inherits IMyInterface

The problem solved by adding a code behind file MyComponent.razor.cs and write the inheritance code there but I wonder that is it possible to have multiple inheritance of interfaces in a razor file?

Answer 1

Multiple inheritance is not possible in C#, and Blazor template generates C# classes. So you can not inherits multiple base classes. However, you can @implements multiple interfaces.

An example would be as follows:

@implements IEventListener
@implements IInterface

I guess it is just a confusion over terms. You inherit a class but you implement an interface