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13723 :: Beginner needs help with passing objects by reference

• warehouse_enjoyer (orginal) [2026-02-16T00:09:10+01:00] view original

  I'm making a simple game with Nim and the kirpi game framework (https://github.com/erayzesen/kirpi) as a learning project. I want to draw different images to the screen depending on the state of the program. I was hoping I could do something like

  
  import kirpi
  
  var tex1, tex2: Texture # Texture belongs to kirpi
  var currTex: Texture
  
  currTex= tex1
  
  # ...and then render or re-assign currTex at some point later
  Run

  But it gives me the following error:

  Error: '=copy' is not available for type <Texture>; requires a copy because it's not the last read of 'tex1'; routine: game

  How can I accomplish this? I think references might be the answer, but I've never used a programming language with explicit pointers and I couldn't really parse the examples online (sorry).

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• Ghazali (orginal) [2026-02-16T05:32:33+01:00] view original

  I think You should ask this in kirpi forums or discussions to get fast response,

  Although I never used kirpi but I think there is problem in how you are using it not Nim I think Texture type in the Kirpi framework is likely a resource managed

  I think you should add ref like this this var tex1, tex2: ref Texture and var currTex: ref Texture and use new for loading that tex1 = new(Texture)

  Try this and let us know, I am not a game dev but I use to handle this kind of error in rust(Move errors I use to get) and zig(there I need to use Use * and &) and I think texture are often non copyable / non cloneable.

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• xigoi (orginal) [2026-02-16T07:43:38+01:00] view original

  I would try something like this:

  
  var tex1, tex2: Texture
  var currTex: ref Texture
  new(currTex) # only call this once
  
  currTex[] = tex1
  Run

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• janAkali (orginal) [2026-02-16T08:07:48+01:00] view original

  In Nim, most types follow copy semantics (they are copied on assignment). If you need a reference, use ref or ptr - here's a good primer.

  ref is a safer interface, but you can't create a reference to an existing object. Instead, create a ref version of your object and dereference it to get plain Texture:

  
  var tex1, tex2: ref Texture = new Texture
  loadTexture(tex1[], "someFile,png")
  loadTexture(tex2[], "otherFile.png")
  
  var currTex: ref Texture = tex1
  drawTexture(currTex[])
  Run

  ptr is an unsafe reference. You can use it to create a reference to an existing object, but it's your responsibility to ensure it's not stale or dangling.

  
  var tex1, tex2: Texture
  
  var currTex: ptr Texture = addr tex1
  drawTexture(currTex[])
  Run

  Another option is to not use references at all and just keep Textures in an array-like structure and store index IDs. This is very common in game development:

  
  var textures: seq[Texture]
  
  proc addTexture(tex: Texture): int =
    textures.add tex
    textures.high  # Returns the index of the new texture
  
  proc drawTexture(idx: int) =
    drawTexture(textures[idx])
  
  var tex1, tex2: Texture
  
  let id1 = addTexture(tex1)
  let id2 = addTexture(tex2)
  
  var currTex = id1
  drawTexture(currTex)
  Run

  Note: I've never used kirpi myself. These examples are just to show the idea.

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• planetis (orginal) [2026-02-16T10:47:54+01:00] view original

  I would hope that Kirpi used some form of convenience layer, such as a TextureManager, so that beginners wouldn’t need to be exposed to the quirks of raylib.

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