Here are the pitfalls you need to pay attention to when using Go!-Golang-php.cn

Here are the pitfalls you need to pay attention to when using Go!

藏色散人

Release： 2021-12-15 15:30:26

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This article is provided by the golang tutorial column to introduce you to some pitfalls that you need to pay attention to when using Go. I hope it will be helpful to friends in need!

Pitfalls of Go that need to be noted

Pitfalls that need to be noted

The advantage of Go lies in its convenient coroutine programming and its strong performance in network processing. . However, in order to pursue simplicity of use, the Go language is very different from other languages. Here are some main pitfalls to pay attention to:

1. The class may accidentally implement an interface (it happens to contain the interface of this interface) implementation), the semantics of the implementation may differ from what is expected by the interface contract.

2. := and = are easy to confuse

3. The zero value problem of the class. If Map has a zero value, it can be queried but cannot be assigned.

4. Reference type If the value is passed, the original value will still be modified. What are the reference types

5, slice trap, if the capacity is sufficient, it is passed by reference

6, nil interface value

Pit 2~Pit 6 code Examples are as follows:

package main
import (
    "fmt"
    "time"
)
func catchError() {
    if err := recover(); err != nil {
        fmt.Println(err)
    }
}
func hole2() {
    a := 1
    if time.Now().Year() > 2020 {
        a := 2 // 一不小心加了一个冒号
        println(a)
    }
    println(a)
}
func hole3() {
    defer catchError()
    var m0 map[string]string
    println("key:", m0["key"])
    m0["key"] = "val" // 报错：assignment to entry in nil map
}
type Hole4 struct {
    Name    string
    Slices  []string
    MyMap   map[string]string
    Channel chan int
}
func hole4() {
    a := Hole4{
        Name:    "a",
        Slices:  []string{"a"},
        MyMap:   map[string]string{"key": "a"},
        Channel: make(chan int),
    }
    go func() {
        for n := range a.Channel {
            fmt.Println(n)
        }
    }()
    b := a
    b.Name = "b"
    b.Slices[0] = "b"
    b.MyMap["key"] = "b"
    b.Channel <- 999
    fmt.Println(a)
    fmt.Println(b)
}
func hole5() {
    slice1 := make([]string, 1, 1)
    slice1[0] = "1"
    temp1 := slice1
    temp1 = append(temp1, "1")
    temp1[0] = "2"
    fmt.Println(slice1)
    slice9 := make([]string, 1, 9)
    slice9[0] = "1"
    temp2 := slice9
    temp2 = append(temp2, "1")
    temp2[0] = "2"
    fmt.Println(slice9)
}
type Cache interface {
    Name()
}
type RedisCache struct{}
func (RedisCache) Name() {}
func hole6() {
    defer catchError()
    var redis1 *RedisCache = nil
    var redis2 Cache = redis1
    if redis2 != nil {
        println("entering...")
        redis2.Name() // 报错：nil pointer dereference
    }
}
func main() {
    hole2()
    hole3()
    hole4()
    hole5()
    hole6()
}

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