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Go Tip: Embedding Example with interfaces
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| package main | |
| import ( | |
| "fmt" | |
| ) | |
| type GreetingsService interface { | |
| SayHello() string | |
| SayGoodMorning() string | |
| } | |
| type EnglishService struct { | |
| Country string | |
| } | |
| func (EnglishService) SayHello() string { return "hello!" } | |
| func (EnglishService) SayGoodMorning() string { return "good morning!" } | |
| type SpanishService struct{} | |
| func (SpanishService) SayHello() string { return "hola!" } | |
| func (SpanishService) SayGoodMorning() string { return "buenos dias!" } | |
| type GiveMeYourMoneyService struct { | |
| GreetingsService | |
| Country string | |
| } | |
| func (GiveMeYourMoneyService) SayGoodMorning() string { return "$$$" } | |
| func main() { | |
| e := EnglishService{Country: "Neverland"} | |
| fmt.Printf("EnglishService: %+v\n", e) | |
| fmt.Printf("EnglishService.SayHello %v\n", e.SayHello()) | |
| fmt.Printf("EnglishService.GoodMorning %v\n", e.SayGoodMorning()) | |
| o := GiveMeYourMoneyService{GreetingsService: &e, Country: "Sokovia"} | |
| fmt.Printf("FancierService: %+v\n", o) | |
| fmt.Printf("FancierService.SayHello: %s\n", o.SayHello()) | |
| fmt.Printf("FancierService.GoodMorning: %s\n", o.SayGoodMorning()) | |
| // This panics because you already assigned it to the specific type, | |
| // you will need to re-instantiate "o" and specify the value again | |
| // o.GreetingsService = &SpanishService{} | |
| var e1 *EnglishService = o.GreetingsService.(*EnglishService) | |
| fmt.Printf("original.Country: %s\n", e1.Country) | |
| //- | |
| o = GiveMeYourMoneyService{GreetingsService: &SpanishService{}, Country: "Pueblo Viejo"} | |
| fmt.Printf("FancierService: %+v\n", o) | |
| fmt.Printf("FancierService.SayHello: %s\n", o.SayHello()) | |
| fmt.Printf("FancierService.GoodMorning: %s\n", o.SayGoodMorning()) | |
| } |
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