# plugin code in plugin/hello.go
package main

import "fmt"

var V int

func F() { fmt.Printf("Hello, number %d\n", V) }


# main in main.go
package main

import "plugin"

func main() {
	p, err := plugin.Open("plugin/hello.so")
	if err != nil {
		panic(err)
	}

	v, err := p.Lookup("V")
	if err != nil {
		panic(err)
	}
	f, err := p.Lookup("F")
	if err != nil {
		panic(err)
	}
	*v.(*int) = 7
	f.(func())() // prints "Hello, number 7"

	p, err = plugin.Open("plugin/hello2.so")
	if err != nil {
		panic(err)
	}
	v, err = p.Lookup("V")
	if err != nil {
		panic(err)
	}
	f, err = p.Lookup("F")
	if err != nil {
		panic(err)
	}
	_ = v
	// *v.(*int) = 7
	f.(func())() // prints "Hello, number 7"
}

go build -trimpath -ldflags "-pluginpath=plugin/hot-$(date +%s)" -buildmode=plugin -o plugin/hello.so plugin/hello.go
go build -trimpath -ldflags "-pluginpath=plugin/hot-$(date +%s)" -buildmode=plugin -o plugin/hello2.so plugin/hello.go

go run -trimpath main.go

Hello, number 7
Hello, number 7

panic: plugin.Open("plugin/hello"): could not find symbol V: dlsym(0x100205980, plugin/hot-1670990324.V): symbol not found

goroutine 1 [running]:
main.main()
        ./main.go:8 +0x4ae
exit status 2