?? operator in nimrod

nullcoalesce.nim

template `??`*(value, default: expr): expr =
  if value == nil: default
  else: value

template `??`*[T](value : ref T, default : ref T) : ref T =
  if value == nil: default
  else: value

template `??`*[T](value : ref T, default : T) : T =
  if value == nil: default
  else: value[]

var someStr: string# = "Hello"
echo someStr ?? "world!"

type
  PPerson = ref TPerson
  TPerson = object
    name: string

proc `$`*(person: TPerson): string = person.name
proc `$`*(person: ref TPerson): string = person.name

var person : PPerson #= PPerson(name: "Jim")
var otherPerson : PPerson #= PPerson(name: "John") 
echo person ?? otherPerson ?? TPerson(name: "James")