How do we tell the compiler that our type implements the interface?

Technical Discussion
1

At the interview, I was asked such a question that put me into a stupor. As I understand tech guy wanted to know if I understand what the concept of interfaces in Go is based on. So after some research didn’t find the answer. Any idea how to answer this question?

type name interface {} is not a valid answer

2

The compiler will consider a given type beeing of a given interface, if and only if all methods of that interface are implemented.

There is no need to tell the compiler that this struct shall be of interface Foo.

3

To make sure that your struct matches a given interface at compile time use this snippet:

// for pointers to struct
type MyType struct{}
var _ MyInterface = (*MyType)(nil)

// for struct literals
var _ MyInterface = MyType{}

See https://medium.com/@matryer/golang-tip-compile-time-checks-to-ensure-your-type-satisfies-an-interface-c167afed3aae

1 Like
4

short answer:

We don’t

i.e. the compiler figures it out for itself.

5

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