Go 言語 interface 使い方のおぼえがき

package main

import (
    "fmt"
)

type IF interface {
    setter(any)
    getter() (any)
}

type struct_aaa struct {
    prop   string ;
}

type struct_bbb struct {
    prop   int ;
}

func (ctx *struct_aaa) setter(arg any){
    ctx.prop = arg.(string) ;
}

func (ctx *struct_aaa) getter() (any){
    return ctx.prop ;
}

func (ctx *struct_bbb) setter(arg any){
    ctx.prop = arg.(int) ;
}

func (ctx *struct_bbb) getter() (any){
    return ctx.prop ;
}

func set(i IF,v any){
    i.setter(v) ;
}

func get(i IF) (any){
    return i.getter() ;
}

func case_01(){
    fmt.Printf("case_01\n") ;
    var a struct_aaa ;
    var b struct_bbb ;

    var if_a IF = &a ;
    var if_b IF = &b ;

    set(&a,"ABC")
    set(&b,123)

    fmt.Printf("A-1-1[%V]\n",a.prop) ;
    fmt.Printf("B-1-1[%V]\n",b.prop) ;

    fmt.Printf("A-1-2[%V]\n",get(&a)) ;
    fmt.Printf("B-1-2[%V]\n",get(&b)) ;

    fmt.Printf("A-1-3[%V]\n",if_a.getter()) ;
    fmt.Printf("B-1-3[%V]\n",if_b.getter()) ;
}

func case_02(){
    fmt.Printf("case_02\n") ;
    var if_a IF = &struct_aaa{} ;
    var if_b IF = &struct_bbb{} ;

    if_a.setter("xyz") ;
    if_b.setter(222) ;

    fmt.Printf("A-2[%V]\n",if_a.getter()) ;
    fmt.Printf("B-2[%V]\n",if_b.getter()) ;
}

func case_03(){

    fmt.Printf("case_03\n") ;

    var if_a IF = &struct_aaa{"ppp"} ;
    var if_b IF = &struct_bbb{333} ;

    fmt.Printf("A-3[%V]\n",if_a.getter()) ;
    fmt.Printf("B-3[%V]\n",if_b.getter()) ;
}

func main(){

    case_01() ;
    case_02() ;
    case_03() ;

    fmt.Printf("Done.\n") ;
}

実行結果

case_01
A-1-1[%!V(string=ABC)]
B-1-1[%!V(int=123)]
A-1-2[%!V(string=ABC)]
B-1-2[%!V(int=123)]
A-1-3[%!V(string=ABC)]
B-1-3[%!V(int=123)]
case_02
A-2[%!V(string=xyz)]
B-2[%!V(int=222)]
case_03
A-3[%!V(string=ppp)]
B-3[%!V(int=333)]
Done.