Delphi thiscall calling convention

Question

I need to call non-static C++ member functions

Hence i need to use the thiscall calling convention.

Delphi doesn't support this calling convention.

So before i can call any of the member functions i have to manually push the parameters in the stack.

  asm
    mov ecx, myClassPointer
  end;

This works fine but i am looking for a better way to do this.

At the moment i am calling the asm code everytime with the classpointer before calling the function, which isn't nice.

As i am no Delphi expert i am wondering if you can declare your own calling convention or automate the calling of those thiscall class methods.

Answer 1

You have the following options:

• Write adapters in asm to call the function. This is your current solution, and as you know the approach is brittle and awkward.
• Write a C++ adapter that presents an interop friendly interface.

The latter option is, in my view, the correct solution. The C++ code is not suitable for interop. Exposing C++ classes through interop is simply wrong. It places unreasonable demands on the consumer. Reasonable approaches include COM and plain C style interop as found in Win32.

Write an adapting C++ DLL that consumes the unreasonable C++ classes and exposes a proper interop friendly interface. The adapter is written in C++ and so is capable of consuming the C++ code. But then it exports an interop friendly variant of the interface that can be readily called from any tool chain.