process-oo.go

/* start prcess/process.go */
package process

type Processer struct{ 
    fetch Fetch // use processor's field
}

func (p *Processor) Process(x string) { // as processer metho
   fetch.Fetch(x)
}
/* end prcess/process.go */

/* start fetch/fetch.go */
package fetch

type Fetch interface {
    Fetch(x string)
}

type httpFetch struct {
}

// ............

func NewHttpFetch() Fetch {
     return &httpFetch
}
/* end fetch/fetch.go */

/* start main.go */
package main

func main() {
    hf := fetch.NewHttpFetch()
    p := process.Processer{
      fetch: hf, 
    }
    p.Process("11211")
}
/* end main.go */