GO Interfaces and Polymorphism

Question 1

How does Go determine if a type implements an interface?

Accepted Answer

The type must have all methods in the interface with matching signatures

Answer

Go uses implicit interface satisfaction: a type implements an interface if it defines all the interface's methods with identical signatures, requiring no explicit declaration.

Question 2

What is the empty interface `interface{}` (or `any`) equivalent to?

Accepted Answer

A type that holds any value since all types satisfy it

Answer

The empty interface has no methods, so every type satisfies it, allowing `interface{}` (or `any` in Go 1.18+) to hold a value of any type.

Question 3

What is a type assertion in Go?

Accepted Answer

Extracting the concrete value and type from an interface at runtime

Answer

A type assertion `v.(T)` extracts the underlying concrete value of type `T` from an interface value, panicking if the concrete type is not `T`.

Question 4

What does a type switch allow you to do in Go?

Accepted Answer

Select a code branch based on the dynamic type of an interface value

Answer

A type switch uses `switch v := i.(type)` to branch on the concrete type stored in an interface, running the matching case.

Question 5

Can a Go interface be embedded in another interface?

Accepted Answer

Yes, to compose larger interfaces from smaller ones

Answer

Go supports interface embedding, allowing you to compose interfaces; for example, `io.ReadWriter` embeds `io.Reader` and `io.Writer`.

GO - Golang Online Test Practice Test

GO - Golang Online Test Practice Test

GO Interfaces and Polymorphism