nimforum mirror - Invalid type: 'proc' in this context 'proc (ui: NimUI, btn: Button)' for proc

JD (orginal) [2018-12-15T04:16:02+01:00] view original

This is a repost from github, but I'd be glad for some insight.

Every time I try to compile my nim program I get the same error. Invalid type: 'proc' in this context 'proc (ui: NimUI, btn: Button)' for proc

I'm trying to implement a simple ui in Nim with sdl2.

Button is an reference object with a field 'action: proc' that is set to a callback proc testOut() during initialization (it just does a simple echo).

The line that the error occurs on is..

 handleInput*(ui: NimUI, btn: Button) =

I made the equivalent work for callback types NOT embedded in objects, just not for variables stored on reference objects. I tried using {.closure.} and {.cdecl.} but I'm not 100% on if I'm using those correctly. I've also tried setting the return type.

Everything works if I remove the callback from the type and initialization procedure of button.

Read the docs and I see that I should be using maybe {.cdecl.} or {.procvar.} but I tried both. Docs say to amend the actual procedure I'm passing, but I tried that too, no dice. Didn't add a return type because I'm not returning anything. testOut just to test passing procedures for callbacks.

in testsdl.nim (just using it to stub main() to get everything started)


import nimui

proc main() =
  newNimUI("Nimrod UI", 0, 0, 1280, 720)
  
  main()

in nimui.nim


import sdl2


type
  SDLException* = object of Exception
  
  Input {.pure.} = enum none, quit
  
  Game = ref object
    inputs: array[Input, bool]
    renderer: RendererPtr
  
  Element = ref object of RootObj
    rect: Rect
  
  NimUI = ref object
    title: cstring
    x, y, w, h: cint
    window: WindowPtr
    renderer: RendererPtr
    inputs: array[Input, bool]
    children: ref seq[Element]
  
  Button = ref object of Element
    clicked: bool
    hovered: bool
    clickAction: proc #problem line

proc testOut() =
  echo("onClick triggered!")
  discard

proc newGame(renderer: RendererPtr): Game =
  new result
  result.renderer = renderer

template sdlFailIf*(cond: typed, reason: string) =
  if cond: raise SDLException.newException(reason & ", SDL error: " & $getError())

proc toInput(key: Scancode): Input =
  case key
  of SDL_SCANCODE_Q: Input.quit
  else: Input.none

#but here is where the actual issue occurs according to the command line
proc getInput*(ui: NimUI, btn: Button) =
  var event = defaultEvent
  var xmouse:cint = 0
  var ymouse:cint = 0
  while pollEvent(event):
    case event.kind
    of QuitEvent:
      ui.inputs[Input.quit] = true
      btn.clicked = true
    of MouseMotion:
      xmouse = event.motion.x
      ymouse = event.motion.y
      #check if mouse is within the bounding box of the button
      if xmouse >= btn.rect.x and xmouse <= btn.rect.x+btn.rect.w and ymouse >= btn.rect.y and ymouse <= btn.rect.y+btn.rect.h:
        btn.hovered = true
      else:
        btn.hovered = false
    of MouseButtonDown:
      btn.clicked = true
      ui.inputs[Input.quit] = true
    else:
      discard

proc newButton*(x, y, w, h: cint, onclick: proc()): Button =
  new(result)
  result.clicked = false
  result.hovered = false
  result.rect = (x, y, w, h)
  result.clickAction = onclick
  return result


proc render(ui: NimUI, el: Element) =
  ui.renderer.setDrawColor(r = 110, g = 132, b = 174) #reset draw color
  ui.renderer.clear()
  
  
  ui.renderer.setDrawColor(r=128, g=128, b=128)
  ui.renderer.fillRect(el.rect)
  
  
  
  # Show the result on screen
  ui.renderer.present()


proc newNimUI*(title: cstring, x, y, w, h: cint) =
  var ui = new(NimUI)
  
  ui.title = title
  ui.x = x
  ui.y = y
  ui.w = w
  ui.h = h
  
  sdlFailIf(not sdl2.init(INIT_VIDEO or INIT_TIMER or INIT_EVENTS)):
    "SDL2 initialization failed"
  
  # defer blocks get called at the end of the procedure, even if an
  # exception has been thrown
  defer: sdl2.quit()
  
  sdlFailIf(not setHint("SDL_RENDER_SCALE_QUALITY", "2")):
    "Linear texture filtering could not be enabled"
  
  ui.window = createWindow(title = title,
    x = SDL_WINDOWPOS_CENTERED, y = SDL_WINDOWPOS_CENTERED,
    w = w, h = h, flags = SDL_WINDOW_SHOWN)
  sdlFailIf ui.window.isNil: "Window could not be created"
  defer: ui.window.destroy()
  
  ui.renderer = ui.window.createRenderer(index = -1,
    flags = Renderer_Accelerated or Renderer_PresentVsync)
  sdlFailIf ui.renderer.isNil: "Renderer could not be created"
  defer: ui.renderer.destroy()
  
  # Set the default color to use for drawing
  ui.renderer.setDrawColor(r = 110, g = 132, b = 174)
  
  var btn = newButton(64, 64, 196, 64, testOut)
  while not ui.inputs[Input.quit]:
    
    ui.boxGetInput(btn)
    ui.render(btn)

Gratitude to anyone that can grant some insight into what I'm doing wrong here.

Mirror of forum.nim-lang.org

4474 :: Invalid type: 'proc' in this context 'proc (ui: NimUI, btn: Button)' for proc