GO Interfaces and Polymorphism 3

Question 1

What is the `error` type in Go?

Accepted Answer

A built-in interface with method `Error() string`

Answer

The `error` type is a built-in interface with a single method `Error() string`, so any type with that method satisfies it.

Question 2

Which interface from `io` represents a type that can be written to?

Accepted Answer

io.Writer

Answer

`io.Writer` requires a `Write(p []byte) (n int, err error)` method and represents any destination that accepts a stream of bytes.

Question 3

What is method promotion through embedding in Go?

Accepted Answer

A struct embedding another type gains access to its methods directly

Answer

When a struct embeds another type, the embedded type's methods are promoted to the outer struct, allowing them to be called directly and satisfying interfaces.

Question 4

What keyword is used to embed a type anonymously in a struct?

Accepted Answer

Just the type name without a field name

Answer

Anonymous (embedded) fields are declared with just the type name (and no explicit field name), e.g., `type S struct { T }` embeds `T` in `S`.

Question 5

How does Go's `sort.Interface` enable custom sorting?

Accepted Answer

By implementing Len, Less, and Swap methods on a custom type

Answer

`sort.Interface` requires `Len() int`, `Less(i, j int) bool`, and `Swap(i, j int)` methods; any type implementing these can be sorted with `sort.Sort`.

GO - Golang Online Test Practice Test

GO - Golang Online Test Practice Test

GO Interfaces and Polymorphism 3