An in-depth chat about methods in golang (tutorial)

Golang is a modern programming language that was born to solve the shortcomings of C and Java. Due to its efficiency, ease of learning, and high reliability, Golang has become the language of choice for many large companies. Methods in Golang are an extremely powerful feature because they allow us to better modularize and organize our code. In the following article, we will learn methods in Golang and understand how they interact with our code.

What are Golang methods?

In Golang, a method is a function for a custom type. In other words, when you define a type and want to perform certain operations on that type, you define methods to accomplish those operations. Methods are often called behaviors of a type because they allow you to define how the type should behave.

Methods in Golang are slightly different from those in other programming languages. They cannot exist alone. Instead, they must be bound to a type to indicate that they belong to that type. This means that when you define a method, you must specify the type to bind to. This is done using the "()" syntax between the method name and the receiver type. The following is a sample code for defining methods in Golang:

type Person struct {
    Name string
    Age  int
}

func (p Person) GetName() string {
    return p.Name
}

func (p Person) GetAge() int {
    return p.Age
}

In the above code, we define a type named Person, and then define two methods GetName and GetAge. Each method has a receiver that specifies the type to which the method is bound. In this case the receiver is of type Person. When we call p.GetName(), the method will take an instance of type Person as parameter.

How to define Golang method?

In Golang, defining methods is very simple. We can use the following syntax to convert a function into a method:

func (t Type) methodName(parameter list) {
 //方法内容
}

Among them, Type represents the type of method to be bound, and methodName represents the method name you want to use. The receiver is a parameter and can be a value receiver or a pointer receiver.

In the following sample code, we define a type named Car and a method named Drive:

type Car struct {
    brand string
    model string
}

func (c Car) Drive() {
    fmt.Printf("Driving %s %s\n", c.brand, c.model)
}

In the above code, we define a type named Car type, and then defines a Drive method. This method receives an instance of the Car type named c as a parameter, which it will use to output a message.

How to use Golang methods?

In Golang, the usage is very simple. Once a method is defined, we can apply the method to instances of that type using the "." operator.

For example:

car := Car{
    brand: "BMW",
    model: "M5",
}

car.Drive()

In the above code, we create a Car type called car and assign it a value with "BMW" and "M5" make and model . We then call this method using the Drive function.

Value Receiver and Pointer Receiver

In Golang, there is also a different type of receiver: pointer receiver. Pointer receivers are very similar to value receivers, but there are some important differences when using them. Pointer receivers use the "*" operator before the type name.

Use a value receiver or a pointer receiver depending on what you want to do. Value receivers are usually the best choice when you just need to read instance properties. If you want to modify an instance's properties, you need to use a pointer receiver.

The following sample code demonstrates how to use a pointer receiver:

func (c *Car) SetBrand(brand string) {
    c.brand = brand
}

In the above code, we define a method called SetBrand and bind it using a pointer receiver to Car type. Therefore, when the method is called, the method will receive a pointer to the Car instance, not the Car instance itself. This allows us to modify the properties of that instance.

Summary

Methods in Golang are powerful tools for handling types. They make code more modular and reusable, and provide programmers with a convenient way to define the behavior of a type. Whether you are new to Golang or an expert, understanding methods in Golang is essential for writing high-quality code.

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