Object Inheritance

objectinheritance.nim

type # Fine with ref object
  T = object of RootObj
    myValue: string
  S1 = object of T
  S2 = object of T

method speak(x: T)  = echo "T Hello ", x.myValue
method speak(x: S1) = echo "S1 Meow ", x.myValue
method speak(x: S2) = echo "S2 Woof ", x.myValue

echo "creating initial objects of types S1, S2, and T"
var a = S1(myValue: "Green")
a.speak
var b = S2(myValue: "Blue")
b.speak
var u = T(myValue: "Blue")
u.speak

echo "Making copy of a as u, colors and types should match"
u = a
u.speak
a.speak

# This used to output:
#
# creating initial objects of types S1, S2, and T
# S1 Meow Green
# S2 Woof Blue
# T Hello Blue
# Making copy of a as u, colors and types should match
# S1 Meow Green
# S1 Meow Green
#
# Now it outputs:
#
# creating initial objects of types S1, S2, and T
# S1 Meow Green
# S2 Woof Blue
# T Hello Blue
# Making copy of a as u, colors and types should match
# T Hello Green
# S1 Meow Green