是否可以在Go中的单值上下文中有选择地获取返回值？

Question

A simple example:

package main

import "fmt"

func hereTakeTwo() (x, y int) {
    x = 0
    y = 1
    return
}

func gimmeOnePlease(x int){
    fmt.Println(x)
}

func main() {
    gimmeOnePlease(hereTakeTwo()) // fix me
}

Is it possible to pass only first returned value from hereTakeTwo() without using an explicit _ assignment? Example of what I would like to avoid:

func main() {
    okJustOne, _ := hereTakeTwo()
    gimmeOnePlease(okJustOne)
}

What I want is to make gimmeOnePlease function able to receive an undefined number of arguments but take only first one OR a way to call hereTakeTwo function and get only first returned value without the necessity to use _ assignments.

Or on a last resort (crazy idea) use some kind of adapter function, that takes N args and reurns only first one, and have something like:

func main() {
    gimmeOnePlease(adapter(hereTakeTwo()))
}

Why? I'm just testing the boundaries of the language and learning how flexible it can be to some purposes.

Answer 1

No, you cannot do that apart from one special case described in the Spec:

As a special case, if the return values of a function or method g are equal in number and individually assignable to the parameters of another function or method f, then the call f(g(parameters_of_g)) will invoke f after binding the return values of g to the parameters of f in order. The call of f must contain no parameters other than the call of g, and g must have at least one return value.

The best you can do besides the temporary variables (which are the best option) is this:

func first(a interface{}, _ ...interface{}) interface{} {
    return a
}

func main() {
    gimmeOnePlease(first(hereTakeTwo()).(int))
}

Playground: http://play.golang.org/p/VXv-tsYjXt

Variadic version: http://play.golang.org/p/ulpdp3Hppj