GO Interfaces and Polymorphism 2

Question 1

Which of the following best describes polymorphism in Go?

Accepted Answer

Using interface variables to call methods on different concrete types

Answer

Go achieves polymorphism through interfaces: a variable of interface type can hold any concrete type that satisfies it, and method calls dispatch to the concrete type.

Question 2

What happens when you call a method on a nil interface value?

Accepted Answer

Panics with 'nil pointer dereference'

Answer

Calling a method on a nil interface panics because there is no underlying concrete type or value to dispatch the call to.

Question 3

What is the difference between a nil interface and an interface holding a nil pointer?

Accepted Answer

A nil interface has no type; an interface with a nil pointer has a type but nil value

Answer

A nil interface (`var i I = nil`) has both type and value as nil; an interface holding a typed nil pointer has a type set but a nil value, so it is not equal to nil.

Question 4

Which built-in Go function can be used to verify at compile time that a type implements an interface?

Accepted Answer

A blank identifier assignment: `var _ MyInterface = (*MyType)(nil)`

Answer

The idiom `var _ MyInterface = (*MyType)(nil)` causes a compile error if `*MyType` does not implement `MyInterface`, serving as a compile-time check.

Question 5

Can a value type and a pointer type both satisfy the same interface in Go?

Accepted Answer

Yes, if both define the required methods with matching receivers

Answer

Both `T` and `*T` can satisfy interfaces if they each define the required methods with the appropriate receiver type.

GO - Golang Online Test Practice Test

GO - Golang Online Test Practice Test

GO Interfaces and Polymorphism 2