c++/cli pass (managed) delegate to unmanaged code

by

Yes, you want Marshal::GetFunctionPointerForDelegate(). Your code snippet is missing the managed function you’d want to call, I just made one up. You will also have to declare the managed delegate type and create an instance of it before you can get a function pointer. This worked well:

#include "stdafx.h"

using namespace System;
using namespace System::Runtime::InteropServices;

#pragma managed(push, off)
typedef void (* UnmanagedSummer)(int arg);

void UnmanagedMethod(int a, int b, UnmanagedSummer sum)
{
    int result = a + b;
    sum(result);
}
#pragma managed(pop)

ref class Test {
    delegate void ManagedSummer(int arg);
public:
    static void Run() {
        Test^ t = gcnew Test();
        ManagedSummer^ managed = gcnew ManagedSummer(t, &Sum);
        IntPtr stubPointer = Marshal::GetFunctionPointerForDelegate(managed);
        UnmanagedSummer functionPointer = static_cast<UnmanagedSummer>(stubPointer.ToPointer());
        UnmanagedMethod(1, 2, functionPointer);
        GC::KeepAlive(managed);    // Important: ensure stub can't be collected while native code is running
        System::Diagnostics::Debug::Assert(t->summed == 3);
    }
    void Sum(int arg) {
        summed += arg;
    }
    int summed;
};

int main(array<System::String ^> ^args)
{
    Test::Run();
    return 0;
}

More Related Contents:

  1. Delegates in swift?
  2. C++/CLI Mixed Mode DLL Creation
  3. Function Pointers in Java
  4. Calling C# code from C++, but ExecuteInDefaultAppDomain() is too limited
  5. How to call managed code from unmanaged code?
  6. expected ‘void (**)(void *, const char *)’ but argument is of type ‘void (*)(void *, const char *)
  7. How do function pointers in C work?
  8. Clean up Excel Interop Objects with IDisposable
  9. “unpacking” a tuple to call a matching function pointer
  10. How to post messages to an STA thread running a message pump?
  11. How does a delegate work in objective-C?
  12. C#: Difference between ‘ += anEvent’ and ‘ += new EventHandler(anEvent)’
  13. Excel Interop – Efficiency and performance
  14. Using a STL map of function pointers
  15. Super-simple example of C# observer/observable with delegates
  16. How to get function’s name from function’s pointer in Linux kernel?
  17. C# pattern to prevent an event handler hooked twice [duplicate]
  18. Use a .jar java library API in C#?
  19. 5 years later, is there something better than the “Fastest Possible C++ Delegates”?
  20. What’s the point of a lambda expression?
  21. How to make a Swift String enum available in Objective-C?
  22. Error with address of parenthesized member function
  23. No definition found for GetActiveObject from System.Runtime.InteropServices.Marshal C#
  24. generic member function pointer as a template parameter
  25. Do function pointers need an ampersand [duplicate]
  26. Passing an arbitrary function as a parameter in Go
  27. Return a value from an Event — is there a Good Practice for this?
  28. Should cookie values be URL encoded?
  29. Does Func.BeginInvoke use the ThreadPool?
  30. Is it good idea to use “Control.CheckForIllegalCrossThreadCalls = false” [duplicate]

Leave a Comment