**Krux02:** _in function parameters, you don't need var keyword. Parameters are
passed by immutable reference by default, only when you want to change the
argument in the function you need the var declaration._
This is currently not specified, unless you use `{.bycopy.}` or `{.byref.}`.
Value parameters can either be passed by value or by reference. If you specify
`{.bycopy.}` for each of the object types above, you will actually run into a
bug:
{.pragma: byX, bycopy.}
type
animal {.byX.} = object of RootObj
dog {.byX.} = object of animal
name: string
cat {.byX.} = object of animal
name: string
method say(self: animal) = discard
method say(self: dog) = echo self.name, ": woof!"
method say(self: cat) = echo self.name, ": meow?"
proc make_noise(a: animal) =
a.say; a.say; a.say
proc main =
var d: dog = dog(name: "Snoopy")
var c: cat = cat(name: "Garfield")
d.make_noise
c.make_noise
main()
