Golang函数指针作为结构的一部分

Question

我有以下代码:

type FWriter struct {
    WriteF func(p []byte) (n int,err error)
}

func (self *FWriter) Write(p []byte) (n int, err error) {
    return self.WriteF(p)
}

func MyWriteFunction(p []byte) (n int, err error) { 
    // this function implements the Writer interface but is not named "Write"
    fmt.Print("%v",p)
    return len(p),nil
}

MyFWriter := new(FWriter)
MyFWriter.WriteF = MyWriteFunction
// I want to use MyWriteFunction with io.Copy
io.Copy(MyFWriter,os.Stdin)

我想要做的是创建一个Writer接口来包装MyWriteFunction,因为它没有命名为"Write",我不能将它用于任何需要"Writer"接口的东西.

这段代码不会起作用,因为它抱怨:

method MyWriterFunction is not an expression, must be called

我在这做错了什么？如何将WriteF设置为MyWriteFunction？

注意:我尽可能地简化了这个问题,实际上我有一个具有MyWriteFunction和一个普通Write函数的结构,所以它有点复杂......(如果有更好的方法来解决我的这个问题)那么我很高兴听到它!)

谢谢!!

---

编辑::我注意到我的拼写错误并修复了它(MyWriterFunction - > MyWriteFunction)

我认为我过分简化了这个问题,误导了我的原意.在匿名评论和peterSO发表评论之后,我重新创建了错误以更好地展示我的问题:

package main

import (
    "fmt"
    "io"
    "strings"
)

type ProxyWrite interface {
    Write(p []byte) (n int, err error)
    SpecialWrite(p []byte) (n int, err error)
}

type Implementer struct {
    counter int
}

func (self Implementer) Write(p []byte) (n int, err error) {
    fmt.Print("Normal write: %v", p)
    return len(p),nil
}

func (self Implementer) SpecialWrite(p []byte) (n int, err error) {
    fmt.Print("Normal write: %v\n", p)
    fmt.Println("And something else")
    self.counter += 1
    return len(p),nil
}


type WriteFunc func(p []byte) (n int, err error)

func (wf WriteFunc) Write(p []byte) (n int, err error) {
    return wf(p)
}

func main() {
    Proxies := make(map[int]ProxyWrite,2)
    Proxies[1] = new(Implementer)
    Proxies[2] = new(Implementer)

    /* runs and uses the Write method normally */
    io.Copy(Proxies[1], strings.NewReader("Hello world"))
    /* gets ./main.go:45: method Proxies[1].SpecialWrite is not an expression, must be called */
    io.Copy(WriteFunc(Proxies[1].SpecialWrite), strings.NewReader("Hello world"))
}

我希望它澄清我在第一次尝试时要表达的意思.

有什么想法吗？

Answer 1

您的代码中存在拼写错误,但无论如何都不需要将func包装到结构中.相反,您可以只定义包装函数的WriteFunc类型,并且可以定义Write方法.这是一个完整的例子.

package main

import (
    "fmt"
    "io"
    "strings"
)

type WriteFunc func(p []byte) (n int, err error)

func (wf WriteFunc) Write(p []byte) (n int, err error) {
    return wf(p)
}

func myWrite(p []byte) (n int, err error) {
    fmt.Print("%v", p)
    return len(p), nil
}

func main() {
    io.Copy(WriteFunc(myWrite), strings.NewReader("Hello world"))
}

Answer 2

修正MyWriterFunction/ MyWriteFunction拼写错误.例如,

package main

import (
    "fmt"
    "io"
    "os"
)

type FWriter struct {
    WriteF func(p []byte) (n int, err error)
}

func (self *FWriter) Write(p []byte) (n int, err error) {
    return self.WriteF(p)
}

func MyWriteFunction(p []byte) (n int, err error) {
    // this function implements the Writer interface but is not named "Write"
    fmt.Print("%v", p)
    return len(p), nil
}

func main() {
    MyFWriter := new(FWriter)
    MyFWriter.WriteF = MyWriteFunction
    // I want to use MyWriteFunction with io.Copy
    io.Copy(MyFWriter, os.Stdin)
}