在不同的操作系统上运行时选择func的正确方法

Question

I really like the cross-compile/platform ease for many tasks that I can get with GO. I have a question regarding, I guess, the equivalent of a #ifdef / #else type of construct for executing/compiling a function based upon the operating system.

Here's the scenario - let's say I have a function that inserts information into the OS's control structures to launch a process at the next time the user starts up their system. On Windows I would update the 'RUN/RUNONCE' registry entry for the user, on MAC there would be a plist entry, etc.

In essence, I'd like to be able to write someone analogous to this (or have overloaded OS specific functions):

func setStartupProcessLaunch () {
    if [OS is Windows] {
        updateRegistry(){}
    } else if [OS is Darwin] {
        updatePlist(){}
    } else if [OS is Linux] {
        doLinuxthing() {}
    }
}

Given the static compilation, any of the routines that aren't called would be flagged as a compilation error. So ideally, I'd like to surround my 'doSpecificOS()' functions in #ifdef WINDOWS, #ifdef MAC type of blocks -- what's the proper way to accomplish this? My hope is that I don't need to create several project trees of the same program for each OS platform.

Answer 1

You could put your functions in an array or map if they all the take the same number/kinds of arguments and have the same return type.

Here's an example to illustrate:

package main

import (
"fmt"
)

var functionMap = map[string]func(int)int{}
var functionArray = [2]func(int)int{nil, nil}

func windowsFunc(x int) int {
    fmt.Printf("Hi from windowsFunc(%d)
", x)
    return 0 
}

func linuxFunc(x int) int {
    fmt.Printf("Hi from linuxFunc(%d)
", x)
    return 1
}


func main() {
    functionMap["Windows"] = windowsFunc
    functionMap["Linux"] = linuxFunc

    functionArray[0] = windowsFunc
    functionArray[1] = linuxFunc

    fmt.Printf("Calling functionMap[\"Windows\"]: ")
    functionMap["Windows"](123)

    fmt.Printf("Calling functionArray[1]: ")
    functionArray[1](456)
}

And the output is:

Calling functionMap["Windows"]: Hi from windowsFunc(123)
Calling functionArray[1]: Hi from linuxFunc(456)