golang method implementation

Golang is an open source programming language that is ideal for developing large-scale applications. Golang provides a series of features that make it easier for developers to write code, one of which is methods. A method is a function that can be associated with a structure type. It can access the data members in the structure type and provide functions and services to the application. In this article, we will explore how to implement various functions and services using Golang’s approach.

Introduction

Method is a basic concept in object-oriented programming that allows us to bind behavior and data together. In Golang, methods are implemented by associating functions with struct types. A method can be thought of as a special function that can only access data members of the type with which it is associated. Therefore, methods provide a mechanism to encapsulate data and code, making the code more flexible and easier to maintain.

Define methods

In Golang, methods are defined by associating functions with structure types. For example, we can define a Rectangle structure type and define an Area() method to calculate its area:

type Rectangle struct {
    width, height float64
}

func (r Rectangle) Area() float64 {
    return r.width * r.height
}

In this example, we first define a Rectangle structure type and include Two data members width and height. Then, we define an Area() method whose receiver receives a variable r of type Rectangle and returns its area as a result.

Notice that there is an r Rectangle enclosed in parentheses before the function definition, where r is the receiver of the method, which determines which structure type the method is associated with. In this case, the Area() method is associated with the Rectangle type, so we can use the variables of that type (r) to access its data members (width and height).

Call method

Once we define a method, we can call the method through an instance of the structure type. For example, we can create a Rectangle instance and call its Area() method:

r := Rectangle{width: 10, height: 5}
area := r.Area()

In the above code, we first create a Rectangle instance r and set its width (width) to 10, The height is 5. We then call its Area() method to calculate its area and store the result in the variable area.

Structure pointer as receiver

In the above example, the receiver we defined is a value type. We can change the fields of the value type, but these changes will not affect the original structure. Instances are affected. If you want the method to mutate the original structure instance, you need to declare the receiver as a pointer to a value type. For example, we can define a Scale() method to scale the size of a Rectangle instance:

func (r *Rectangle) Scale(factor float64) {
    r.width = r.width * factor
    r.height = r.height * factor
}

In this example, we first change the type of the receiver to a pointer type. In the method body, we change the width and height fields of the structure variable r to scale its size. Since r is a pointer to a structure variable, these changes affect the original structure instance.

Selection of receiver type

In Golang, the type of receiver has an impact on the method. Although using value types as receivers is appropriate in most cases, if you need to modify the original structure instance, you need to use pointer types as receivers. At the same time, if a method needs to copy the value of the receiver multiple times, it will be very time-consuming and memory-consuming when processing large amounts of data. In this case, we can choose to use a pointer type as the receiver to avoid these copies.

Summary

In this article, we learned the basic concepts and usage of methods in Golang, and how to use methods to associate with structure types to implement various functions and services. We learned about the definition, calling and selection of receiver types in Golang. Understanding these contents can help us better understand object-oriented programming in Golang.

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