The Go Programming Language

6.4 Method Values and Expressions

Usually we select and call a method in the same expression, as in p.Distance(), but it’s possible to separate these two operations. The selector p.Distance yields a method value, a function that binds a method (Point.Distance) to a specific receiver value p. This function can then be invoked without a receiver value; it needs only the non-receiver arguments.

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p := Point{1, 2} q := Point{4, 6} distanceFromP := p.Distance // method value fmt.Println(distanceFromP(q)) // "5" var origin Point // {0, 0} fmt.Println(distanceFromP(origin)) // "2.23606797749979", √5 scaleP := p.ScaleBy // method value scaleP(2) // p becomes (2, 4) scaleP(3) // then (6, 12) scaleP(10) // then (60, 120) ...