Go supports OOP: use struct instead of class

In fact, go is very similar to php and java in object-oriented processing, but go has no class.

Is Go Object Oriented?

There is no concept of Class in Go, it is not a pure object-oriented programming language.

Go has types and methods, and also supports an object-oriented programming style.But there is no type hierarchy structure.Interfaces in Go are types that define a collection of methods. These interfaces are simple and generic to use, and they also support embedding into other types, making it easy to provide something similar but not identical to subclasses.

struct instead of class

Go doesn't have class but has struct , you can add methods to struct.You can also bind data to methods that operate on data.It's like Class.

package modulestype Users struct {Name stringAge intStatus bool}func (u Users) SetUserStatus(){u.Status = false;fmt.Printf("Set the status of %s to %t \n ",u.Name,u.Status)}// main.gopackage mainfunc main(){user := modules.Users{Name: "Tom",Age: 12Status: false}user.SetUserStatus()}Copy code

The above code defines the structure Users, and then binds a setUserStatus method, in which the properties of the structure can be manipulated.In the mian file, we can initialize a variable user of the User structure, and then operate the method of the variable.This is very similar to Class.

New() function instead of constructor

In C# and Java, a class is created with a constructor that takes no parameters.Then in Go you can use the New() method to play the role of a constructor.

In the demo above, we defined and initialized a variable user of the Users structure.What happens when we define the Users struct with zero values?

package mainfunc main(){var u modules.Usersu.setUserStatus()}// Execute go run main.go and the result is as follows:Set the status to falseCopy code

As you can see, a variable created with a zero value has no valid name , and there is no name value in the output, just an empty string.In the Java language, we often use constructors to solve this problem, using parameterized constructors to create valid objects.For example, in a Java program:

// in java languagepublic class Users{public string NameUsers(name){this.name = name;}}// useUsers user = new User("Tom")Copy code

Go does not support constructors.To prevent other packages from defining a variable with a zero value when accessing a structure of type Users, it will have an invalid effect.By providing a function named New that initializes the type Users with the desired value.

In Go, it is a convention to name functions that create values ​​of type T as NewT(params).This will act as a constructor.When there is only one type in the package, the convention is to name the function New(params), not NewT(params).

So we use it correctly as follows:

package modulestype users struct {name stringage intstatus bool}func New(name string, age int, status bool) Users {user := users{name, age, status}return user}func (u Users) setUserStatus(){u.status = false;fmt.Printf("Set the status of %s to %t \n ",u.name,u.status)}Copy code

You can see from the above code:

• We changed the structure Users to private, and its fields are also set to private to prevent access by other external packages.Because we don't need to access the users field from anywhere other than the modules package, unless there are other specific scenarios that require it.
• In addition, a public New function is added, the parameter of this function is the field of the user structure, and returns a newly created user instance.

Use simply calls the New function, which prevents the creation of unusable user struct type values.This is also the only way to create a user.

// usepackage mainfunc main(){user := modules.New("Jack", 30, true)user.setUserStatus()}Copy code

So, although Go doesn't support class , we can effectively use struct instead of class , and use New function instead of constructor.This enables OOP.

Author: Activist No. 6
Link: https://juejin.cn/post/7120926520662556686
Source: Rare Earth Nuggets