Calling a D function directly from C++

Question

I\'ve gone through http://dlang.org/cpp_interface.html and in all of the examples, even those where some C++ code calls some D code, the main function resides in D (and so t

Answer 1

Yes it is possible, (your mileage may vary depending on the C++ compiler used.)

Firstly, you will have to initialized the D runtime, either from the C++ or the D side.

cpptestd.d:

import std.stdio;

extern (C++) void CallFromCPlusPlusTest() {
  /*
   * Druntime could also be initialized from the D function:
  import core.runtime;
  Runtime.initialize();
  */
  writeln("You can call me from C++");
  //Runtime.terminate(); // and terminated
}

Compile with: dmd -c cpptestd.d

cpptest.cpp:

#include 

using namespace std;

void CallFromCPlusPlusTest();
extern "C" int rt_init();
extern "C" int rt_term();

int main() {
  cout << "hello world"<<"\n";
  rt_init(); // initialize druntime from C++
  CallFromCPlusPlusTest();
  rt_term(); // terminate druntime from C++
  return 0;
}

Compile and link with: g++ cpptest.cpp cpptestd.o -L/path/to/phobos/ -lphobos2 -pthread

This works for me on Linux.