Go: What is the difference between pointer and value receiver?

Pointer receiver (*T) — method operates on the original value via pointer, can modify it, avoids copying. Value receiver (T) — method operates on a copy, changes are discarded.

The receiver type determines how the method interacts with the struct. Pointer receivers get a pointer — mutations persist. Value receivers get a snapshot — mutations are local to the method.

1type Player struct {
2    health int
3    name   string
4}
5
6// Pointer receiver — modifies health
7func (p *Player) TakeDamage(amount int) {
8    p.health -= amount
9}
10
11// Value receiver — read-only
12func (p Player) IsAlive() bool {
13    return p.health > 0
14}
15
16hero := Player{health: 100, name: "Hero"}
17hero.TakeDamage(30)
18fmt.Println(hero.IsAlive())  // true

When to use:

• Pointer — any method that mutates the receiver, or when the struct is large (> 2-3 fields).
• Value — small structs (1-2 fields) with read-only methods, especially when immutability is desired.

Common mistakes:

• Inconsistent receiver types within the same type — pick one and stick with it.
• Value receiver on a method that mutates — the caller sees no change, silent bug.
• Forgetting that nil pointer receivers are valid in Go — calling a method on a nil pointer can cause panics if the method dereferences it.
• Using pointer receiver for tiny value types (like Point) where copying is cheaper than indirection.