Go language-make traps and closure functions

Go language make Traps

a := make([]int, 3)a = append(a, 1, 2, 3)切片大小变成６

anonymous functions

An anonymous function is a function implementation that does not need to define a function name and can be directly assigned to a variable or run directly

Closed Package

Go的匿名函数是一个闭包,闭包是可以包含自由（未绑定到特定对象）变量的代码块，这些变量不在这个代码块内或者,任何全局上下文中定义，而是在定义代码块的环境中定义。要执行的代码块（由于自由变量包含,在代码块中，所以这些自由变量以及它们引用的对象没有被释放）为自由变量提供绑定的计算环境（作用域）。

The value of a closure is that it can be used as a function object or as an anonymous function.

Closures are literal definitions: Closures are entities that are composed of functions and their associated reference environments (that is, closures = functions + reference environments). This is literally hard to understand, especially for programmers who have been programming with imperative languages.

The life cycle of a variable in a closure is the same as the period of a closure variable

A closure in go, a function and an entity that is combined with its associated reference environment.

Go has a variable of a function type, so that although you cannot declare another function directly in a function, you can declare a variable of a function type in a function, where the function is called closure (closure).

Example 1:

package mainimport "fmt"func getSequence() func(i int) int {            sum:=0             return func(i int) int {                sum = sum +i                return sum    }}func main(){        nextNumber := getSequence()        fmt.Println(nextNumber(1))        fmt.Println(nextNumber(1))        fmt.Println(nextNumber(1))        nextNumber1 := getSequence()        fmt.Println(nextNumber1(1))        fmt.Println(nextNumber1(1))}

Run results

12312

Example 2

package mainimport "fmt"func getSequence() func() int {    sum:=0    return func() int {                sum += 1                return sum             }}func main(){        nextNumber := getSequence()        fmt.Println(nextNumber())        fmt.Println(nextNumber())        fmt.Println(nextNumber())        nextNumber1 := getSequence()        fmt.Println(nextNumber1())        fmt.Println(nextNumber1())}

Run results

12312

Example 3

package mainimport "fmt"func main(){        sum1 := 10        getSequence := func() func() int {                     sum:=0                     return func() int {                                fmt.Println(sum1)                                sum += 1                                return sum                     }        }        nextNumber := getSequence()        fmt.Println(nextNumber())        fmt.Println(nextNumber())        fmt.Println(nextNumber())        nextNumber1 := getSequence()        fmt.Println(nextNumber1())        fmt.Println(nextNumber1())        fmt.Println("end:",sum1)}

Run results

101102103101102end: 10

Go language-make traps and closure functions