Calling a method with a pointer receiver by an object instead of a pointer to it?

Question

v is an object of Vertex, and Scale is a method for a pointer to Vertex. Then why is v.Scale(10) not wrong,

Answer 1

It's the Go automatic dereferencing:

From https://golang.org/ref/spec#Method_values:

As with selectors, a reference to a non-interface method with a value receiver using a pointer will automatically dereference that pointer: pt.Mv is equivalent to (*pt).Mv.