goparameter-passingslicevariadic-functions

How can I pass a slice as a variadic input?


I have a function func more(... t). I'm wondering if it's possible to use a slice to populate a list of arguments ... .

I'm trying to solve the following program. Basically to mimic a normal shell which receives the command as a string. Command function requires a "list" of arguments and I don't see how I can convert a string into a such list

import "os/exec"
import "strings"
func main(){
    plainCommand  := "echo hello world"
    sliceA := strings.Fields(plainCommand)
    cmd := exec.Command(sliceA)
}

Solution

  • The Go Programming Language Specification

    Passing arguments to ... parameters

    If f is variadic with final parameter type ...T, then within the function the argument is equivalent to a parameter of type []T. At each call of f, the argument passed to the final parameter is a new slice of type []T whose successive elements are the actual arguments, which all must be assignable to the type T. The length of the slice is therefore the number of arguments bound to the final parameter and may differ for each call site.


    Package exec

    func Command

    func Command(name string, arg ...string) *Cmd
    

    Command returns the Cmd struct to execute the named program with the given arguments.

    The returned Cmd's Args field is constructed from the command name followed by the elements of arg, so arg should not include the command name itself. For example, Command("echo", "hello")


    For example,

    package main
    
    import (
        "fmt"
        "os/exec"
    )
    
    func main() {
        name := "echo"
        args := []string{"hello", "world"}
        cmd := exec.Command(name, args...)
        out, err := cmd.Output()
        if err != nil {
            fmt.Println(err)
        }
        fmt.Println(string(out))
    }
    

    Output:

    hello world