VB to C# Translation

In VB (ASP.NET)

Application("myapp")= Server.CreateObject("APP.Engine")

aa = Application("myapp").myMethod(2)

works.

In C# I tried

Application["myapp"]= Server.CreateObject("APP.Engine")

but

Application["myapp"].myMethod(2)

fails with

'object' does not contain a definition for 'myMethod'

H开发者_Go百科ow can I expose the public interface in C#?

If you have access to the defining type (i.e. not a raw COM object), you can simply cast:

((APP.Engine)Application["myapp"]).myMethod(2);

If you are using c# 4.0, you can do:

dymamic myApp = Application["myapp"];
myApp.myMethod(2);

Otherwise you will have to use dynamic method invocation using reflection and Type.InvokeMember(...)

You need to cast to the correct class first, like:

((APP.Engine)Application["myapp"]).myMethod(2)

Cast the result of Application["myapp"] to the correct type, like so:

((APP.Engine)Application["myapp"]).myMethod(2);

Other options include creating a local reference and using that instead.

This basically happens as C# is strongly typed language. When you call Application you are actually calling a collection of type Object. The collection is actually an array of Object. We take it as object because it will enable you to store almost anything to the collection.

Now Application["myapp"] will eventually return an object of System.Object type.

So you need to typecast the object to your type.

App.Engine obj = Application["myapp"] as App.Engine;
if(obj !=  null)
  obj.myMethod(2);

The object obj is a reference to the actual type and the compiler will not throw any exception if you call myMethod(2).

Just remember one thing while converting code from VB to C# is, C# is the strongly typed language and before you access any type, you will need to convert it. However same wasn't required in VB.

So for this example you would need to use App.Engine for type conversion.

((APP.Engine)Application["myapp"]).myMethod(2)