go 基础7
更多干货
代码地址：
https://github.com/csy512889371/learndemo/tree/master/go/golearn
概述
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函数式编程
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闭包
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资源管理出错处理
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defer调用 确保在函数结束时调用
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defer 先入后出
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代码
package main
import "fmt"
func adder() func(int) int {
sum := 0
return func(v int) int {
sum += v
return sum
}
}
type iAdder func(int) (int, iAdder)
func adder2(base int) iAdder {
return func(v int) (int, iAdder) {
return base + v, adder2(base + v)
}
}
func main() {
// a := adder() is trivial and also works.
a := adder2(0)
for i := 0; i < 10; i++ {
var s int
s, a = a(i)
fmt.Printf("0 + 1 + ... + %d = %d\n",
i, s)
}
}函数实现接口
package main
import (
"bufio"
"fmt"
"io"
"strings"
"golearn/functional/fib"
)
type intGen func() int
func (g intGen) Read(
p []byte) (n int, err error) {
next := g()
if next > 10000 {
return 0, io.EOF
}
s := fmt.Sprintf("%d\n", next)
// TODO: incorrect if p is too small!
return strings.NewReader(s).Read(p)
}
func printFileContents(reader io.Reader) {
scanner := bufio.NewScanner(reader)
for scanner.Scan() {
fmt.Println(scanner.Text())
}
}
func main() {
var f intGen = fib.Fibonacci()
printFileContents(f)
}