我可以制作函数`extern“c”`吗？

Question

I have some cpp files, and I want to combine them with LuaJit using FFI.

But the problem is that, I have to add extern "c" symbols for almost every function to make it possible for FFI to access them.

Is there a simpler way to make this done?

Answer 1

Several functions can be placed inside a single extern "C" block. This allows you to type extern "C" only once for each header file.

extern "C" {
    void function1();
    void function2();
}

Answer 2

Though it is non-portable, you could implement a function signature and generates the Mangled name using the name mangling protocol to find the symbol name for FFI.

Gcc and Clang on Linux use the Itanium C++ ABI Name Mangling Rules, which can be found here.

On Windows, MSVC uses a non-documented name mangling scheme.

Answer 3

Yes. Define a simple, minimal, wrapper API and export it:

// NOTE: Exported functions do heavy parley and medical-research leveraging C++ under the hood (and only and the hood).
extern "C" {
  void achieve_world_peace(void);

  void treat_cancer(void);
}