不能在Golang中调用Println时摆脱fmt前缀

Question

I tried http://tour.golang.org/#1

package main

import "fmt"

func main() {
    Println("Hello World")
}

This generates error :

prog.go:3: imported and not used: "fmt"
prog.go:6: undefined: Println
 [process exited with non-zero status]

Program exited

Does it mean I am obliged to prefix Println with "fmt" package name ? In other languages it isn't mandatory.

Answer 1

You will have to prefix a function if it is not in the current package.

What you can do however is create an alias for this package:

import f "fmt"

func main() {
    f.Println("Hello World")
}

Or "rename" the function:

import "fmt"

var Println = fmt.Println

func main() {
    Println("Hello World")
}

Or use . as alias (it may be what you would like most):

import . "fmt"

func main() {
    Println("Hello World")
}

Note that in that case, the alias is not blank. From the specifications of Go:

A qualified identifier is an identifier qualified with a package name prefix. Both the package name and the identifier must not be blank.

QualifiedIdent = PackageName "." identifier .

And another example from the same specifications:

import   "lib/math"         math.Sin
import m "lib/math"         m.Sin
import . "lib/math"         Sin