如何在 Go 中使用 C++

2021-12-11 00:00:00 wrapper c++ go

在新的 Go 语言中，我如何调用 C++ 代码?换句话说，我如何包装我的 C++ 类并在 Go 中使用它们?

In the new Go language, how do I call C++ code? In other words, how can I wrap my C++ classes and use them in Go?

推荐答案

更新:我已经成功地将一个小型测试 C++ 类与 Go 链接起来

Update: I've succeeded in linking a small test C++ class with Go

如果您使用 C 接口包装 C++ 代码，您应该能够使用 cgo 调用您的库(请参阅 $GOROOT/misc/cgo/gmp 中的 gmp 示例).

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).

我不确定 C++ 中类的想法是否真的可以在 Go 中表达，因为它没有继承.

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

这是一个例子:

我有一个 C++ 类定义为:

I have a C++ class defined as:

// foo.hpp
class cxxFoo {
public:
  int a;
  cxxFoo(int _a):a(_a){};
  ~cxxFoo(){};
  void Bar();
};

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

我想在 Go 中使用.我会用C接口

which I want to use in Go. I'll use the C interface

// foo.h
#ifdef __cplusplus
extern "C" {
#endif
  typedef void* Foo;
  Foo FooInit(void);
  void FooFree(Foo);
  void FooBar(Foo);
#ifdef __cplusplus
}
#endif

(我使用 void* 而不是 C 结构，所以编译器知道 Foo 的大小)

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

实现是:

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

完成所有这些后，Go 文件是:

with all that done, the Go file is:

// foo.go
package foo
// #include "foo.h"
import "C"
import "unsafe"
type GoFoo struct {
     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));
}

我用来编译这个的makefile是:

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)

尝试使用以下方法进行测试:

Try testing it with:

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

您需要使用 make install 安装共享库，然后运行 ??make test.预期输出为:

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_.6
6g -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.cgo3.6
1
PASS

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