What is the difference between value receivers and pointer receivers?
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Core Competency
Assesses fundamental understanding of Go conventions, runtime behavior, and memory/performance considerations.
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Evaluation Criteria
Hiring managers look for precision, avoidance of ambiguous jargon, and ability to explain trade-offs under real production conditions.
Comprehensive Model Answer
Verified Solution
A method receiver can be a value (func (u User) Name() string) or a pointer (func (u *User) SetName(n string)).
- A value receiver operates on a copy, so it cannot mutate the caller's value. Its method set is available on both values and pointers.
- A pointer receiver can mutate, avoids copying large structs, and its method set is only on pointers. Go automatically takes the address when you call a pointer method on an addressable value.
type Counter struct{ n int }
func (c *Counter) Inc() { c.n++ }
func (c Counter) Get() int { return c.n }
The practical rule: if any method mutates state, make all methods pointer receivers for consistency. Small immutable types can use value receivers. A frequent surprise is that a value stored in a map is not addressable, so you cannot call a pointer method on it. Interfaces are satisfied by the method set, so pointer receivers mean only *T implements the interface, not T.
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