Fiddling with scoping in Go

scope.go

package main

import (
  "fmt"
  "log"
)

// Many functions in Go return an error as the last argument, nil for no error
func f() (int, error) {
  return 42, nil
}

func main() {
  // i is visible within the loop
  // whatever is on the opening { line is also in scope, all the way to the closing }
  // makes sense
  for i := 0; i < 10; i++ {
    fmt.Println(i)
  }
  // i is undeclared

  // likewise, if x is declared as part of an if statement,
  // it won't be available beyond the if/else construct
  if x, err := f(); err != nil {
    log.Fatal("booyah")
  } else {
    fmt.Println(x) // still in scope
  }
  // x is undeclared

  // an alternative
  // doing the assignment and comparison on separate lines allows
  // y to be used after the err check
  y, err := f()
  if err != nil {
    log.Fatal("fail")
  }
  fmt.Println(y)

  // actually, just doing the declaration before the if scope works too
  // but you lose the type inference of the short assignment (:=) operator. :(
  var z int
  if z, err = f(); err != nil {
    log.Fatal("huzzah")
  }
  fmt.Println(z)
}