You never modify the result or return anything in `NewChildWindow`. And since
ChildWindow is an object and not a ref object, it will initialize all its
fields to their default values which is why cw has no children.
I think what you want to do is in line with the super constructor calls in
normal OOP languages, but this is not possible in Nim due to object slicing
going away and the constructor pattern in Nim (newObj) being to create objects
in the constructor instead of modifying a parameter. The solution I can give
you doesn't have object inheritance and is a bit more idiomatic:
type
Window = ref object
title: string
width, height: int
children: seq[int]
ChildWindow = object
window, parent: Window
handle: int
proc newWindow*(title: string = "My New window"): Window =
new(result)
result.title = title
result.width = 800
result.height = 600
result.children = @[]
proc addChild*(parent, window: Window): ChildWindow =
result.parent = parent
result.window = window
result.handle = parent.children.len + 1
parent.children.add(result.handle)
var bw = newWindow()
var cw = bw.addChild(newWindow("My new child window"))
echo bw.children.len # 1
echo cw.parent.children.len # 1
echo cw.window.title # My new child window
Run
