go - Go 中的持久化程序

Question

我正在尝试学习 Go，我想我应该从一个我想做一段时间的项目开始(但它似乎太“繁琐”而无法打扰)。基本思想是我有一个程序在 stdin/stdout 上与用户交互，我想编写一个新程序以相同的方式与程序交互(就好像它是一个运行程序的人)。

现在这里的程序很简单，因为它是同步的:您输入一个命令，得到一些输出，然后它就坐在那里等待下一批输入。这看起来并不难，但我无法让这个 I/O 框架正常工作。

package main

import (
    "os/exec"
    "time"
    "bufio"
    "math/rand"
    "fmt"
    "strings"
)

func main() {
    cmd := exec.Command("e")    // A simple program that echos input until it becomes "exit"

    progin, err := cmd.StdoutPipe()
    if err != nil {
        fmt.Println("Trouble with e's stdout")
        panic(err)
    }

    err = cmd.Start()
    if err != nil {
        fmt.Println("Trouble starting e")
        panic(err)
    }

    r := rand.New(rand.NewSource(99))

    buf := bufio.NewReader(progin)
    for {
        // Write stuff
        var toProg string
        if (r.Float64() < .1) {
            toProg = "exit"
        } else {
            toProg = fmt.Sprintf("%d", r.Int)
        }
        fmt.Println("Printing: ", toProg)
        cmd.Stdin = strings.NewReader(toProg + "\n")

        // Read stuff
        time.Sleep(500 * time.Millisecond) // give the program time to generate output

        input, err := buf.ReadString('\n')
        if err != nil {
            fmt.Println("I did *not* like that: ", input)
            panic(err)
        }
        fmt.Println("Received: ", input)

    }
}

有人要吗？

Answer 1

您最大的问题是您正在重新分配命令的标准输入，而不是通过管道传递给它。

这是一个工作版本:

package main

import (
    "bufio"
    "fmt"
    "math/rand"
    "os/exec"
    "time"
)

func main() {
    cmd := exec.Command("./e") // A simple program that echos input until it becomes "exit"

    progin, err := cmd.StdoutPipe()
    if err != nil {
        fmt.Println("Trouble with e's stdout")
        panic(err)
    }

    progout, err := cmd.StdinPipe()
    if err != nil {
        fmt.Println("Trouble with e's stdin")
        panic(err)
    }

    err = cmd.Start()
    if err != nil {
        fmt.Println("Trouble starting e")
        panic(err)
    }

    r := rand.New(rand.NewSource(99))

    buf := bufio.NewReader(progin)
    for {
        // Write stuff
        var toProg string
        if r.Float64() < .1 {
            toProg = "exit"
        } else {
            toProg = fmt.Sprintf("%d", r.Int())
        }
        fmt.Println("Printing: ", toProg)
        progout.Write([]byte(toProg + "\n"))

        // Read stuff
        time.Sleep(500 * time.Millisecond) // give the program time to generate output

        input, err := buf.ReadString('\n')
        if err != nil {
            fmt.Println("I did *not* like that: ", input)
            panic(err)
        }
        fmt.Println("Received: ", input)

    }
}

然后 e.go 进行一些修复:

package main

import (
    "bufio"
    "fmt"
    "os"
    "strings"
)

func main() {
    for {
        buf := bufio.NewReader(os.Stdin)
        input, err := buf.ReadString('\n')

        if err != nil {
            fmt.Println("Echo failed: ", input)
            panic(err)
        }

        if strings.HasPrefix(input, "exit") {
            fmt.Println("Bye!")
            return
        }

        fmt.Print(input)
    }
}