CODEWITHSUNDEEP
c#vb.netdll
Kcoder
Kcoder

Reputation: 3480

DLL Methods Inaccessible in C# but not in VB.NET

I'm in the process of converting a legacy VB.NET application into a C# application. The VB.NET application references an external .DLL (ExternalLib.dll) that has the class MyClass which implements IMyClass.

In VB.NET, this code compiles and executes without problems:

Dim external As New MyClass
external.DoMethod(1)

In C#, this code throws a compile-time error:

MyClass external = new MyClass();
external.DoMethod(1);

'ExternalLib.MyClass' does not contain a definition for 'DoMethod' and no extension method 'DoMethod' accepting a first argument of type 'ExternalLib.MyClass' could be found (are you missing a using directive or an assembly reference?)

Looking at the metadata, IMyClass doesn't have DoMethod(). In VB.NET's Intellisense, DoMethod() does not show up among the other available public methods, but everything compiles and runs just fine.

Upvotes: 1

Views: 369

Answers (2)

Kcoder
Kcoder

Reputation: 3480

The VB.NET application is using late-binding with option strict off to access the hidden method in ExternalLib.dll. Using the dynamic keyword allows for the same behavior in the C# application:

dynamic external = new MyClass();
external.DoMethod(1);

(Kudos to Blorgbeard for pointing me in the right direction.)

Upvotes: 0

Quality Catalyst
Quality Catalyst

Reputation: 6795

Is DoMethod() a static method or an instance method? If it was a static method that would explain why you can't see it in the interface. You need to change your C# code to this:

MyClass.DoMethod(1);

Upvotes: 1

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