Golang 不定参数&匿名函数与闭包

2018-12-31 15:42:15 Albin Wong 1572

语法糖(syntactic sugar) 类型...type本质上是一个数组切片，也就是[]type

### 不定参数
语法糖(syntactic sugar)  
类型...type本质上是一个数组切片，也就是[]type
#### 不定参数类型
```go
func myfunc(args ...int) {
	for _, arg := range args {
		fmt.Println(arg)
	}
}

func main() {
	myfunc(2, 3, 4)
	myfunc(1, 3, 7, 13)
}
```

#### 传递
```go
func myfunc(args ...int) { 
    // 按原样传递
    myfunc3(args...)
    
    // 传递片段，实际上任意的int slice都可以传进去
    myfunc3(args[1:]...)
}
```

#### 任意类型的不定参数
```go
func Printf(format string, args ...interface{}) {
    // ...
}
```

> varg1.go

```go
func MyPrintf(args ...interface{}) {
	for _, arg := range args {
		switch arg.(type) { 
			case int:
				fmt.Println(arg, "is an int value.") 
			case string:
				fmt.Println(arg, "is a string value.") 
			case int64:
				fmt.Println(arg, "is an int64 value.") 
			default:
			    fmt.Println(arg, "is an unknown type.")
		}
	}
}

func main() {
	var v1 int = 1
	var v2 int64 = 234
	var v3 string = "hello" 
	var v4 float32 = 1.234
	MyPrintf(v1, v2, v3, v4)
}
```

#### 匿名函数
由一个不带函数名的函数声明和函数体组成  
```go
func(a, b int, z float64) bool {
    return a*b <int(z)
}
```
匿名函数可以直接赋值给一个变量或者直接执行
```go
f := func(x, y int) int { 
    return x + y
}

func(ch chan int) {
    ch <- ACK
} (reply_chan) // 花括号后直接跟参数列表表示函数调用
```

#### 闭包（closure）
```go
package main

import (
	"fmt"
)

func main() {
	var j int = 5
	a := func() (func()) {
		var i int = 10
		return func() {
			fmt.Printf("i j : %d %d\n", i,j)
		}
	}()

a() // i, j: 10, 5

j *= 2

a() // i, j: 10, 5
}
```

(3) Comments

John Doe- Reply

February 26, 2013 at 1:18 pm
- saqib sarwar- Reply
  
  February 26, 2013 at 1:20 pm
  
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John Doe- Reply

February 26, 2013 at 1:27 pm

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Golang 不定参数&匿名函数与闭包

(3) Comments

John Doe- Reply

saqib sarwar- Reply

John Doe- Reply

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