├── README.md
├── c++
    ├── SConstruct
    ├── c++_interface_lib
    │   ├── interface.cc
    │   └── interface.h
    └── c++_static_lib
    │   ├── work.cc
    │   └── work.h
└── go
    └── src
        ├── cgo_lib
            └── cgo_lib.go
        └── go_prog
            └── go_prog.go


/README.md:
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 1 | # Go-Cpp #
 2 | 
 3 | This project demonstrates how to call C++ code from Go program without
 4 | the need of using SWIG.
 5 | 
 6 | The basic idea is to write a
 7 | [C wrapper](https://github.com/wangkuiyi/go-cpp/tree/master/c%2B%2B/c%2B%2B_interface_lib)
 8 | of
 9 | [C++ code](https://github.com/wangkuiyi/go-cpp/tree/master/c%2B%2B/c%2B%2B_static_lib),
10 | and use `cgo` to call this C wrapper.
11 | 
12 | ## Checkout and Build
13 | 
14 |     git clone -b develop https://github.com/wangkuiyi/go-cpp
15 |     cd go-cpp/c++
16 |     scons
17 |     cd ../go
18 |     export GOPATH=`pwd`
19 |     cd src/go_prog
20 |     go install
21 |     DYLD_LIBRARY_PATH=$GOPATH/../c++/ $GOPATH/bin/go_prog
22 | 
23 | Note that you need to install SCons to build the C++ part.  In order
24 | to install SCons on Mac OS X, you can use Homebrew.
25 | 
26 | If you are using Linux, the last command to run the demo program is:
27 | 
28 |     LD_LIBRARY_PATH=$GOPATH/../c++/ $GOPATH/bin/go_prog
29 | 


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/c++/SConstruct:
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1 | StaticLibrary('cppstaticlib', ['c++_static_lib/work.cc'])
2 | SharedLibrary('cppinterfacelib', ['c++_interface_lib/interface.cc'], LIBS=['cppstaticlib'], LIBPATH='.')
3 | 


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/c++/c++_interface_lib/interface.cc:
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 1 | #include "../c++_static_lib/work.h"
 2 | // Thie file, as a C++ source file, should not include C interfacing
 3 | // header files, i.e., "interface.h".
 4 | 
 5 | extern "C" {
 6 |   long CRandom() {
 7 |     // As the rng is seeded in every call, it is not random at all.
 8 |     RandomNumberGenerator r(1);
 9 |     return r.Rand();
10 |   }
11 | }
12 | 


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/c++/c++_interface_lib/interface.h:
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 1 | #ifndef GO_CPP_CPP_CPP_STATIC_LIB_INTERFACE_H_
 2 | #define GO_CPP_CPP_CPP_STATIC_LIB_INTERFACE_H_
 3 | 
 4 | // This file is to be used by the cgo library, so it should export
 5 | // only C stuff.
 6 | long CRandom();
 7 | // but not any C++ things, for example, CppRandom().
 8 | 
 9 | #endif  // GO_CPP_CPP_CPP_STATIC_LIB_INTERFACE_H_
10 | 


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/c++/c++_static_lib/work.cc:
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1 | #include "work.h"
2 | 
3 | long CppRandom() {
4 |   RandomNumberGenerator r(1);
5 |   return r.Rand();
6 | }
7 | 


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/c++/c++_static_lib/work.h:
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 1 | #ifndef GO_CPP_CPP_CPP_STATIC_LIB_WORK_H_
 2 | #define GO_CPP_CPP_CPP_STATIC_LIB_WORK_H_
 3 | 
 4 | #include <stdlib.h>
 5 | 
 6 | class RandomNumberGenerator {
 7 |  public:
 8 |   RandomNumberGenerator(unsigned int seed) {
 9 |     // A real random number generator should not delegates the work to
10 |     // srandom/random.
11 |     srandom(seed);
12 |   }
13 | 
14 |   long Rand() {
15 |     return random();
16 |   }
17 | };
18 | 
19 | #endif  // GO_CPP_CPP_CPP_STATIC_LIB_WORK_H_
20 | 


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/go/src/cgo_lib/cgo_lib.go:
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 1 | package cgo_lib
 2 | 
 3 | // #cgo CFLAGS: -I../../../c++/
 4 | // #cgo LDFLAGS: -L../../../c++ -lcppinterfacelib
 5 | // #include "c++_interface_lib/interface.h"
 6 | import "C"
 7 | 
 8 | func GoRandom() int {
 9 | 	return int(C.CRandom())
10 | }
11 | 


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/go/src/go_prog/go_prog.go:
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 1 | // If it complains cannot find the shared library when you run this
 2 | // program, please export DYLD_LIBRARY_PATH=<go-cpp/c++> if you use OS
 3 | // X, or export LD_LIBRARY_PATH=<go-cpp/c++> if you use Linux.
 4 | package main
 5 | 
 6 | import (
 7 | 	"cgo_lib"
 8 | 	"fmt"
 9 | )
10 | 
11 | func main() {
12 | 	fmt.Println(cgo_lib.GoRandom())
13 | }
14 | 


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