Go - Methods

go go/book/learninggo

A Method is a function that is associated with a specific type.
Methods are used to add behavior to types, especially custom types like Struct, making them essential for object-oriented programming in Go.
They allow you to define functions that operate on the data contained within a specific instance of a type.

Methods - Practical Go Lessons

Remember

A method is just a function with a receiver argument.

Go - Visibility

Method vs Function

Aspect	Method	Function
Type association	Associated with a specific type via a receiver	Not associated with any specific type
Receiver	Has a receiver parameter	No receiver
Purpose	Adds behavior to a type, supports encapsulation	General-purpose
Interfaces	Can be part of an interface method set	Cannot be part of an interface
Invocation	Called on a specific instance of the type	Called directly by function name

// Method with a receiver of type `Person`
func (p *Person) UpdateName(newName string) {
    p.Name = newName
}
 
// Function without a receiver
func updateName(p *Person, newName string) {
    p.Name = newName
}

Method Receivers: Value vs. Pointer

1. Value Receiver (func (p Person) Greet() {...})

• A copy of the value is made when the method is called.
• The original value remains unchanged if modified within the method.
• Value receivers are typically used when you don’t need to modify the receiver’s data or for small types where copying is inexpensive.

2. Pointer Receiver (func (p *Person) Greet() {...})

• A pointer to the receiver value is passed to the method.
• Modifications made within the method affect the original value.
• Pointer receivers are used when you want the method to modify the receiver’s data or for large types to avoid copying overhead.