// src/pkg1
package pkg1

import "fmt"

var Int = 0
var Map = make(map[string]int)

func init() {
    fmt.Printf("pkg1.Int: %p\n", &Int)
    fmt.Printf("pkg1.Map: %p\n", &Map)
}

// src/pkg2
package pkg2

import "C"
import (
    "fmt"
    "pkg1"
)

//export Load
func Load() {
    fmt.Printf("pkg2.Load...\n")
}

func init() {
    fmt.Printf(">>> pkg2: pkg1.Int: %p\n", &pkg1.Int)
    fmt.Printf(">>> pkg2: pkg1.Map: %p\n", &pkg1.Map)
}

// src/my-cmd/main.go
package main

import "C"

import _ "pkg2"

func main() {}

// src/main.go
package main

// #include <dlfcn.h>
// #cgo LDFLAGS: -ldl
// #include <stdlib.h>
// #include <stdio.h>
//
// void loadPlugin(void *lib) {
//   void (*f)(void) = NULL;
//   char *error = NULL;
//   f = (void (*)(void))(dlsym(lib, "Load"));
//   error = dlerror();
//   if (f == NULL || error != NULL) {
//      fprintf(stderr, "ERROR no such symbol!!! (%s)\n", error);
//      return;
//   }
//   fprintf(stderr, "symbol 'Load' loaded...\n");
//   (*f)();
// }
import "C"

import (
    "fmt"
    "log"
    "pkg1"
    "unsafe"
)

func main() {
    fmt.Printf("main.pkg1.Int: %p\n", &pkg1.Int)
    fmt.Printf("main.pkg1.Map: %p\n", &pkg1.Map)

    fmt.Printf("loading DLL...\n")
    cstr := C.CString("./mylib.so")
    defer C.free(unsafe.Pointer(cstr))
    h := C.dlopen(cstr, C.RTLD_NOW)
    if h == nil {
        log.Fatalf("error loading %s\n", C.GoString(cstr))
    }
    defer C.dlclose(h)

    fmt.Printf("loading plugin...\n")
    C.loadPlugin(h)
    fmt.Printf("loading plugin... [done]\n")

}