Several ways to implement enumeration

There is no enumeration type built in Go language like other languages, but we can implement the function of enumeration in some ways. This article will introduce in detail how to implement enumeration in the Go language and provide code examples.

The concept of enumeration

An enum is a data type composed of a set of named constants. Each constant has a unique name and an integer value. The main purpose of enumeration is to improve the readability and maintainability of the code and avoid the use of magic numbers.

Methods to implement enumeration

1. Use constants

In Go language, constants can be used to implement the function of enumeration. Here is an example:

package main

import "fmt"

const (
    Sunday = iota
    Monday
    Tuesday
    Wednesday
    Thursday
    Friday
    Saturday
)

func main() {
    (Sunday)
    (Monday)
    (Tuesday)
    (Wednesday)
    (Thursday)
    (Friday)
    (Saturday)
}

In this example, we use the iota keyword to automatically generate continuous integer values. Each constant has a unique name and an integer value, incremented from 0.

2. Use structure

Another way to implement enumeration is to use structures. Here is an example:

package main

import "fmt"

type Weekday int

const (
    Sun Weekday = iota
    Mon
    Tue
    Wed
    Thu
    Fri
    Sat
)

func (d Weekday) String() string {
    switch d {
    case Sun:
        return "Sunday"
    case Mon:
        return "Monday"
    case Tue:
        return "Tuesday"
    case Wed:
        return "Wednesday"
    case Thu:
        return "Thursday"
    case Fri:
        return "Friday"
    case Sat:
        return "Saturday"
    default:
        return "Unknown"
    }
}

func main() {
    (Sun)
    (Mon)
    (Tue)
    (Wed)
    (Thu)
    (Fri)
    (Sat)
}

In this example, we define a structure Weekday and use constants to represent different days of the week. We also implement the String method so that we display a friendly name when printing enum values.

3. Use custom types and methods

We can also use custom types and methods to implement more complex enumeration functions. Here is an example:

package main

import "fmt"

type Color string

const (
    Red Color = "red"
    Green Color = "green"
    Blue Color = "blue"
)

func (c Color) IsPrimary() bool {
    switch c {
    case Red, Green, Blue:
        return true
    default:
        return false
    }
}

func main() {
    (())
    (())
    (())
    (Color("yellow").IsPrimary())
}

In this example, we define a custom type Color and use constants to represent different colors. We also implemented a method IsPrimary, which is used to determine whether the color is one of the three primary colors.

Summarize

In Go, although there is no built-in enumeration type, we can use constants, structures, or custom types and methods to implement the functionality of enumeration. These methods can improve the readability and maintainability of the code and avoid the use of magical numbers. In practical applications, the appropriate method can be selected according to specific needs to implement enumeration.

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