How to use C++ in Go?

Update: I've succeeded in linking a small test c++ class with go

If you wrap you c++ code with a c interface you should be able to call your library with cgo (see the example of gmp in $GOROOT/misc/cgo/gmp).

I'm not sure if the idea of a class in c++ is really expressible in go, as it doesn't have inheritance.

Here's an example

I have a c++ class defined as

// foo.hppclass cxxFoo {public:int a;
 cxxFoo(int _a):a(_a){};~cxxFoo(){};voidBar();};// foo.cpp#include<iostream>#include"foo.hpp"void
cxxFoo::Bar(void){
 std::cout<<this->a<<std::endl;}

which I want to use in go. I'll use the c interface

// foo.h#ifdef __cplusplus
extern"C"{#endiftypedefvoid*Foo;FooFooInit(void);voidFooFree(Foo);voidFooBar(Foo);#ifdef __cplusplus
}#endif

(I use a void* instead of a c struct so the compiler knows the size of Foo)

The implementation is

//cfoo.cpp#include"foo.hpp"#include"foo.h"FooFooInit(){
 cxxFoo * ret =new cxxFoo(1);return(void*)ret;}voidFooFree(Foo f){
 cxxFoo * foo =(cxxFoo*)f;delete foo;}voidFooBar(Foo f){
 cxxFoo * foo =(cxxFoo*)f;
 foo->Bar();}

with all that done, the go file is

// foo.go
package foo
// #include "foo.h"import"C"import"unsafe"
type GoFoostruct{
 foo C.Foo;}
func New()(GoFoo){
 var ret GoFoo;
 ret.foo = C.FooInit();return ret;}
func (f GoFoo)Free(){
 C.FooFree(unsafe.Pointer(f.foo));}
func (f GoFoo)Bar(){
 C.FooBar(unsafe.Pointer(f.foo));}

The makefile I used to compile this was

// makefile
TARG=foo
CGOFILES=foo.go
include $(GOROOT)/src/Make.$(GOARCH)
include $(GOROOT)/src/Make.pkg
foo.o:foo.cpp
 g++ $(_CGO_CFLAGS_$(GOARCH))-fPIC -O2 -o $@ -c $(CGO_CFLAGS) $<
cfoo.o:cfoo.cpp
 g++ $(_CGO_CFLAGS_$(GOARCH))-fPIC -O2 -o $@ -c $(CGO_CFLAGS) $<
CGO_LDFLAGS+=-lstdc++
$(elem)_foo.so: foo.cgo4.o foo.o cfoo.o
 gcc $(_CGO_CFLAGS_$(GOARCH)) $(_CGO_LDFLAGS_$(GOOS))-o $@ $^ $(CGO_LDFLAGS)

Try testing it with

// foo_test.go
package foo
import"testing"
func TestFoo(t *testing.T){
 foo :=New();
 foo.Bar();
 foo.Free();}

You'll need to install the shared library with make install, then run make test. Expected output is

gotest
rm -f _test/foo.a _gotest_.66g-o _gotest_.6 foo.cgo1.go foo.cgo2.go foo_test.go
rm -f _test/foo.a
gopack grc _test/foo.a _gotest_.6 foo.cgo3.61
PASS

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