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discard """
cmd: '''nim c -d:nimAllocStats --newruntime $file'''
output: '''button
clicked!
(allocCount: 4, deallocCount: 4)'''
"""
import system / ansi_c
type
Widget* = ref object of RootObj
drawImpl: owned(proc (self: Widget))
Button* = ref object of Widget
caption: string
onclick: owned(proc())
Window* = ref object of Widget
elements: seq[owned Widget]
proc newButton(caption: string; onclick: owned(proc())): owned Button =
proc draw(self: Widget) =
let b = Button(self)
echo b.caption
#result = Button(drawImpl: draw, caption: caption, onclick: onclick)
new(result)
result.drawImpl = draw
result.caption = caption
result.onclick = onclick
iterator unitems*[T](a: seq[owned T]): T {.inline.} =
## Iterates over each item of `a`.
var i = 0
let L = len(a)
while i < L:
yield a[i]
inc(i)
assert(len(a) == L, "the length of the seq changed while iterating over it")
proc newWindow(): owned Window =
proc windraw(self: Widget) =
let w = Window(self)
for i in 0..<len(w.elements):
let e = Widget(w.elements[i])
let d = (proc(self: Widget))e.drawImpl
if not d.isNil: d(e)
result = Window(drawImpl: windraw, elements: @[])
proc draw(w: Widget) =
let d = (proc(self: Widget))w.drawImpl
if not d.isNil: d(w)
proc add*(w: Window; elem: owned Widget) =
w.elements.add elem
proc main =
var w = newWindow()
var b = newButton("button", nil)
let u: Button = b
b.onclick = proc () =
u.caption = "clicked!"
w.add b
w.draw()
# simulate button click:
u.onclick()
w.draw()
dumpAllocstats:
main()
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