Methods

Intermediate · Types & Methods

A method is a function with a receiver. Choose the receiver type deliberately:

• value receiver (r T) — operates on a copy; use for read-only behavior
• pointer receiver (r *T) — can mutate the original; use to change state or avoid copying large values

Methods can be defined on any named type you declare in your package, not only structs.

• methods1 — value (Area) vs pointer (Scale) receivers
• methods2 — a method on a named non-struct type (Celsius)

Resources

• A Tour of Go: Methods
• Effective Go: Pointers vs. Values
• Go by Example: Methods

Exercises

methods1 test

Methods attach behavior to a type. A value receiver (r Rectangle) works on a

Show hint

Value receiver reads; pointer receiver mutates:

func (r Rectangle) Area() float64 { return r.Width * r.Height }
func (r *Rectangle) Scale(f float64) { r.Width *= f; r.Height *= f }

Source

methods2 test

You can define methods on ANY named type you declare, not just structs.

Show hint

Convert the named type to its underlying type for arithmetic:

return float64(c)*9/5 + 32

Source