When it is necessary to modify the receiver and the receiver is a large object or maintain method consistency, pointer receiver should be used; 2. Value receiver is suitable for small objects, basic types, read-only operations or immutable data; 3. Go allows mixing of both, but the interface implementation is limited by method set rules: only the pointer type can implement the pointer receiver method, while the value type cannot meet the interface; 4. In terms of performance, large structures recommend pointer receivers to avoid copy overhead, and small structures can use value receivers; 5. If there is a pointer receiver method for the same type, it is recommended that other methods also use pointer receivers to maintain consistency; 6. Use pointer receivers first when uncertain, unless it is explicitly necessary to avoid modification. Choosing the right recipient can improve code clarity and performance.
In Go, you can choose to use pointer receiver or value receiver when defining methods. This choice may seem small, but it has a practical impact on the behavior, performance and maintainability of the program. The following is a comparison of their usage scenarios and differences from several key perspectives.
1. When should I use a pointer to receive the receiver?
Core principle: You want to modify the receiver itself in the method, or the receiver is a large object.
Typical scenarios for using pointer receivers include:
- ? The method requires modifying the receiver field
- ? The receiver is
structand is large (avoid copy overhead) - ? You want to maintain consistency (some methods of the same type use pointers, and other methods are also recommended to use pointers)
type Person struct {
Name string
Age int
}
// Pointer receiver: can modify the field func (p *Person) GrowUp() {
p.Age
}
// Value recipient: can only read, cannot change the original object (changed as a copy)
func (p Person) Rename(newName string) {
p.Name = newName // will not affect the original object}Call example:
person := Person{Name: "Alice", Age: 25}
person.GrowUp() // Age becomes 26
person.Rename("Bob") // Name will not change to fmt.Println(person.Name) // Still "Alice"2. When can the value recipient be used?
Applicable to: small objects, basic types, no modifications, or immutable data in itself.
Value recipients are safer and more "functional" and are suitable for the following situations:
- ? Recipient is the basic type (such as
int,string) - ?The
structis very small (such as only a few fields), and the copy cost is low - ? The method is just to read the data, not to modify it
- ? The type itself is immutable (such as read-only configuration)
type Counter int
func (c Counter) IsZero() bool {
return c == 0
}
func (c Counter) String() string {
return fmt.Sprintf("%d", c)
} It is natural for the recipient to use value here, because Counter is essentially int , and the copy is cheap, and the method does not modify the state.
3. Mix pointer and value recipient? Go allows, but there are rules
The Go language allows you to mix pointer and value receivers on the same type, but the method set will affect the interface implementation .
Key Difference: Method Set
| Method set of type T | Contains all func (t T) Method() |
|---|---|
| Method set of type *T | Contains all func (t T) Method() and func (t *T) Method() |
This means:
- If the method required by the interface is implemented by the pointer receiver , then * only the pointer type ` T` can satisfy the interface**
- Value type
Tcannot be assigned to this interface variable
type Speaker interface {
Speak()
}
type Dog struct{}
func (d *Dog) Speak() {
fmt.Println("Woof!")
}
var s Speaker = &Dog{} // ? Yes: *Dog implements Speak
// var s2 Speaker = Dog{} // ? Error: Dog does not implement Speak (the method is *Dog)Therefore: If your method uses pointer receiver, remember to use pointer when assigning interface values.
4. Performance considerations: value vs pointer
- Value Receiver : Copy the entire value with each call. For large
struct, the overhead is obvious. - Pointer receiver : only pass the address, the overhead is fixed (usually 8 bytes), but may cause escape and GC pressure.
suggestion:
- Small structure (such as 2-3 fields): There is no problem with the value receiver
- Large structure or uncertain size: priority pointer receiver
Summary: Select a suggestion
| Scene | Recommended recipient type |
|---|---|
| Need to modify the recipient | ? Pointer Receiver |
| The receiver is a large structure | ? Pointer Receiver |
| The method set must satisfy the interface and may be assigned to the interface variable | Note: Pointer Receiver → Only *T can implement the interface |
| Small structure, read-only operation, basic type | ? Value recipient |
| There are already pointer receivers in multiple methods of the same type | It is recommended to use pointers uniformly (avoid confusion) |
? A simple rule of thumb: use pointers to receive when you are uncertain , unless you explicitly want to avoid modification or pursue immutability.
Basically that's it. Go's design allows for flexible choices, but understanding the behavioral differences behind it can only write clearer and less buggy code.
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