Differences in golang method functions

In the Go programming language, we often use methods and functions to perform tasks and return results. Although they both produce the same results, their roles in object-oriented programming are different. In this article, we will analyze the difference between methods and functions in Go.

Definition of methods and functions

In Go, the definitions of functions and methods are similar, but their syntax and usage are different.

In Go, a function is an independent block of program code that can accept parameters and return results. Functions can be called anywhere in the program and do not require specific data structures. Here is a simple function example:

func add(x int, y int) int {
    return x + y
}

Methods are functions associated with a data structure, they have an extra receiver parameter that is of a specific type that is guaranteed to work on a value of that type Perform actions. For example, the following code shows the method definition:

type person struct {
    name string
    age  int
}

func (p person) PrintName() {
    fmt.Println(p.name)
}

In the above code, PrintName() is a method that is defined as a member of the person structure receiver. This means we can only call this method in the person object.

Syntax difference

The syntax of a function is as follows:

func functionName(parameterName type) returnType {
    // Function code goes here
}

And the syntax of a method is as follows:

func (receiverName ReceiverType) MethodName(parameterName type) returnType {
    // Method code goes here
}

In a method, we must specify it before the function name A receiver (also called an object or interface). Receivers can be of any type, including custom types. If the receiver is a pointer, the method can modify its value.

Differences in calling methods

Functions can be called anywhere in the program. For example, the following code demonstrates executing a function at different locations in the program:

func main() {
    fmt.Println(add(1, 2))
    fmt.Println(sayHello())
}

func add(x, y int) int {
    return x + y
}

func sayHello() string {
    return "Hello World!"
}

In contrast, methods can only be called with the object to which they are associated. Here is a simple example:

package main

import "fmt"

type person struct {
    name string
    age  int
}

func (p person) PrintName() {
    fmt.Println(p.name)
}

func main() {
    p := person{"John", 25}
    p.PrintName()
}

In the above method call, the PrintName method can only be called on the person structure type.

Inheritance and Polymorphism

Methods can be inherited between structures, and they can be overridden to implement polymorphism. This is because methods are associated with specific types. This inheritance and polymorphism make Go a powerful object-oriented programming language.

On the other hand, functions cannot be inherited and polymorphic. Because they are agnostic to any particular type, unlike methods, they cannot be overridden to achieve polymorphism.

Summary

Although functions and methods can both produce the same results, they differ in their use and design. Methods can only be called with their associated types and have the characteristics of inheritance and polymorphism. On the other hand, functions are called anywhere in the code and do not have the characteristics of inheritance and polymorphism. Therefore, when writing code, we take these differences into account so that we use methods or functions in the correct context.

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