阅读golang反射文档
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asahi
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- [Golang](#golang)
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- [Get Started](#get-started)
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- [Enable dependency tracking](#enable-dependency-tracking)
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- [go mod init](#go-mod-init)
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- [go mod tidy](#go-mod-tidy)
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- [multi-module workspace](#multi-module-workspace)
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- [go work init](#go-work-init)
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- [go work use](#go-work-use)
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- [Gin框架构建restful api](#gin框架构建restful-api)
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- [向response中写入返回数据](#向response中写入返回数据)
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- [解析request中的数据](#解析request中的数据)
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- [将请求的endpoint注册到server中](#将请求的endpoint注册到server中)
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- [golang generic](#golang-generic)
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- [不使用泛型的代码编写](#不使用泛型的代码编写)
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- [使用泛型的代码编写](#使用泛型的代码编写)
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- [comparable](#comparable)
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- [泛型方法调用](#泛型方法调用)
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- [type constraint](#type-constraint)
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- [Fuzzing](#fuzzing)
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- [unit test编写](#unit-test编写)
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- [fuzz test编写](#fuzz-test编写)
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- [执行fuzz test](#执行fuzz-test)
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- [sync.Pool](#syncpool)
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- [sync.Pool使用示例](#syncpool使用示例)
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- [Pool和垃圾回收](#pool和垃圾回收)
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- [poolCleanup](#poolcleanup)
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- [allPools \& oldPools](#allpools--oldpools)
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- [Proc Pining](#proc-pining)
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- [per-P](#per-p)
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- [local \& localSize](#local--localsize)
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- [PinSlow](#pinslow)
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- [Pool Local](#pool-local)
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- [pool的Put/Get](#pool的putget)
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- [Put](#put)
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- [Get](#get)
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- [slow path](#slow-path)
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- [Sync.once](#synconce)
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- [use case](#use-case)
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- [syntax](#syntax)
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- [iota](#iota)
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- [Get Started](#get-started)
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- [Enable dependency tracking](#enable-dependency-tracking)
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- [go mod init](#go-mod-init)
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- [go mod tidy](#go-mod-tidy)
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- [multi-module workspace](#multi-module-workspace)
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- [go work init](#go-work-init)
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- [go work use](#go-work-use)
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- [Gin框架构建restful api](#gin框架构建restful-api)
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- [向response中写入返回数据](#向response中写入返回数据)
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- [解析request中的数据](#解析request中的数据)
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- [将请求的endpoint注册到server中](#将请求的endpoint注册到server中)
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- [golang generic](#golang-generic)
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- [不使用泛型的代码编写](#不使用泛型的代码编写)
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- [使用泛型的代码编写](#使用泛型的代码编写)
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- [comparable](#comparable)
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- [泛型方法调用](#泛型方法调用)
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- [type constraint](#type-constraint)
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- [Fuzzing](#fuzzing)
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- [unit test编写](#unit-test编写)
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- [fuzz test编写](#fuzz-test编写)
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- [执行fuzz test](#执行fuzz-test)
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- [sync.Pool](#syncpool)
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- [sync.Pool使用示例](#syncpool使用示例)
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- [Pool和垃圾回收](#pool和垃圾回收)
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- [poolCleanup](#poolcleanup)
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- [allPools \& oldPools](#allpools--oldpools)
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- [Proc Pining](#proc-pining)
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- [per-P](#per-p)
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- [local \& localSize](#local--localsize)
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- [PinSlow](#pinslow)
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- [Pool Local](#pool-local)
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- [pool的Put/Get](#pool的putget)
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- [Put](#put)
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- [Get](#get)
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- [slow path](#slow-path)
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- [Sync.once](#synconce)
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- [use case](#use-case)
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- [reflect](#reflect)
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- [reflect basic](#reflect-basic)
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- [Type](#type)
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- [Kind](#kind)
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- [常用方法](#常用方法)
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- [NumField](#numfield)
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- [Field](#field)
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- [syntax](#syntax)
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- [iota](#iota)
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@@ -805,6 +812,66 @@ func (o *Once) doSlow(f func()) {
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}
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```
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## reflect
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### reflect basic
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go reflection基于`Values, Types, Kinds`，其相关类为`reflect.Value, reflect.Type, reflect.Kind`，获取方式如下：
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- `reflect.ValueOf(x interface{})`
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- `refelct.TypeOf(x interface{})`
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- `Type.kind()`
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#### Type
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type用于表示go中的类型，通过`reflect.TypeOf(x interface{})`来进行获取
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```go
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fmt.Println(reflect.TypeOf(Addr{})) // main.Addr
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fmt.Println(reflect.TypeOf(&Addr{})) // *main.Addr
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```
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#### Kind
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kind用于表示`类型`的数据类型，通过`.Kind`来进行获取：
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```go
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fmt.Println(reflect.TypeOf(Addr{}).Kind()) // struct
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fmt.Println(reflect.TypeOf(&Addr{}).Kind()) // ptr
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```
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### 常用方法
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golang反射还提供了其他的一些常用方法。
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#### NumField
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该方法返回struct中的fields数量，如果类型参数其kind不为`reflect.struct`，那么其会发生`panic`
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```go
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fmt.Println(reflect.TypeOf(Addr{}).NumField()) // 2
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```
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#### Field
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该方法允许通过下标来访问struct中的field。
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```go
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t := reflect.TypeOf(Addr{})
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for i := 0; i < t.NumField(); i++ {
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fmt.Println(t.Field(i))
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}
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```
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上述输出为
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```
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{FrmIp string 0 [0] false}
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{DstIp string 16 [1] false}
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```
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根据反射遍历struct中的field，其示例如下：
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```go
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var v interface{} = Addr{FrmIp: "1.2.3.4", DstIp: "7.8.9.10"}
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m := reflect.TypeOf(v).NumField()
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for i := 0; i < m; i++ {
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fn := reflect.TypeOf(v).Field(i).Name
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fv := reflect.ValueOf(v).Field(i).String()
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fmt.Println(fn, fv)
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}
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```
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## syntax
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### iota
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`iota`关键字代表连续的整数变量，`0, 1, 2`，每当`const`关键字出现时，其重置为0
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