In Go language, does the interface still implement in situations like main1?

The implementation mechanism of the Go language interface is different from other languages, and it adopts an implicit implementation method. This article will explain the implementation principle of Go language interface in detail through sample code and answer the question of whether the main1 function implements the interface.

Implicit implementation of Go language interface

In Go, a type automatically implements the interface as long as it implements all methods defined in the interface, without explicit declaration.

For example, define a fruit interface and an apple structure:

 type fruit interface {
    GetName() string
}

type apple struct {
    name string
}

func (a apple) GetName() string {
    return a.name
}

The apple structure implements the fruit interface because it contains GetName() method.

Comparison between main1 function and main function

Now, let's compare the two functions main1 and main :

 // main1 function func main1() {
    apple := apple{name: "apple"}
    fmt.Println(apple.GetName()) // Output "apple"
}

// main function func main() {
    var f fruit
    apple := apple{name: "apple"}
    f = apple
    fmt.Println(f.GetName()) // Output "apple"
}

The main1 function directly creates an apple instance and calls GetName() method. Although the fruit interface is not explicitly used, the apple structure still meets the requirements of fruit interface.

main function declares a variable f of type fruit and assigns apple instance to it. The compiler will check whether apple implements the fruit interface.

in conclusion

1. The apple structure implements the fruit interface because it implements all methods defined in the interface.
2. Although the main1 function does not explicitly use the interface, apple structure still meets the conditions of the interface, so it can be considered main1 indirectly uses the interface.
3. main function explicitly uses the interface, and the compiler will perform type checks to ensure that apple implements the fruit interface.

Therefore, although the main1 function does not directly use the definition of the interface, it can be considered that it indirectly implements the function of the interface because it uses the type that implements the interface. The key is whether the type meets the interface requirements, rather than whether the interface variables are explicitly declared or used.

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