Why Golang doesn’t have “classes”

The current field of computer science has been constantly developing and innovating. In terms of programming languages, object-oriented programming languages ​​that were common in the past, such as Java, C, etc., have now been replaced by new programming languages. Among them, Golang, which is widely loved by developers, is a language that does not support the traditional object-oriented programming model. This article will explore why Golang does not have "classes" and how to implement similar programming models in other ways.

Why Golang doesn’t have “classes”

Golang’s design to remove classes is an attempt to counter traditional object-oriented language design. In traditional object-oriented languages, a class is a fixed program structure that contains properties and methods. Therefore, when designing a system that supports object-oriented programming (OOP, Object-Oriented Programming), it is usually necessary to deal with object-oriented classes.

However, Golang is not just a programming language with object-oriented language features. Its goal is to become a general-purpose language that includes both process-oriented and object-oriented programming paradigms. Therefore, Golang has some very useful programming features, including:

Structure (Struct)

In Golang, unlike traditional object-oriented languages ​​such as Java and C, there are no classes, instead is a "structure", which is a custom type. Through structures, we can organize variables and package them together, and then use methods to operate on these structures.

For example, the following is a simple structure definition:

type Person struct {
    name string
    age  int
}

Example of creating a Person structure:

p1 := Person{name: "John", age: 26}

Call the method of the structure:

p1.hello() //在Person结构中定义的方法

Through structures, we can easily implement class-like operations without the need for fixed class usage in object-oriented programming languages.

Method

The method in Golang is a function that can operate on the structure. By defining methods through structure types, variables can be bound to methods instead of binding methods to classes like traditional object-oriented languages. Methods can be used to manipulate structures and perform operations on them.

For example, for the Person structure defined in the above example, you can define a greeting method:

func (p Person) hello() {
    fmt.Printf("My name is %s, I'm %d years old.\n", p.name, p.age)
}

The method in the above example is defined directly on the structure, which is a bit like object-oriented "Member methods" in programming. In Golang, methods on a structure are usually defined in the structure's definition file, but the definition file is not required.

Interface

In Golang, interface is a custom type. An interface defines the signatures of a set of methods, and a type is considered to implement the interface if it defines all the required methods. A type with an interface can be replaced with an interface and defined with the same set of methods.

Interface is a very important concept in Golang, which can make the relationship between the modules of the program more transparent. When developers provide an interface for a module, they can retain the signature of the called method without having to implement the specific implementation of the module. Subsequent developers may replace it with a richer implementation, which helps enhance the scalability of the program.

Function

Golang’s functions are first-class citizens, which means that functions are objects. Functions can be assigned to variables and can be received as parameters and return values ​​by other functions. This is a very important concept in Golang, because many people think that functions are a more natural way to do object-oriented design.

How to use Golang to implement a "class-like" programming model?

Although Golang itself has no concept of classes, developers can use structures and methods to simulate this programming model. This method is called "instance" in Go.

For example, suppose we want to define class-like operations for a structure named Person:

type Person struct {
    name string
    age  int
}

The following are some methods (similar to class member functions):

func (p *Person) SetName(name string) {
    p.name = name
}
func (p *Person) SetAge(age int) {
    p.age = age
}
func (p *Person) GetAge() int {
    return p.age
}

The above example defines three methods for operating the Person structure: SetName, SetAge and GetAge. The original value of the structure can be modified using pointer parameters.

The following is an example of how to create a Person structure:

p := Person{"Golang", 10}

Where "p" is an "instance" like a class.

Next, we can "create" a new instance of the structure by using a function. Here is an example:

func NewPerson(name string, age int) *Person {
    p := Person{name, age}
    return &p
}

The "NewPerson" function can be used like this and will return a pointer to the "Golang" instance:

p := NewPerson("Golang", 10)

Although "instance" is not like traditional object-oriented "Classes" in programming languages ​​are the same, but the way structures and methods are used in Golang can simulate the concept of classes in a very similar way.

Conclusion

Although there are no classes, Golang's structures and methods reconcile the use of object-oriented and procedural programming paradigms. Using structures and methods, we can implement a programming model similar to classes to manage variables and operations. Therefore, Golang can use these very useful language features even without classes, making it a fast, flexible and powerful web development language.

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