Modding Help SOLVED: Receiving data from RpcPromise

Hello,

I am trying to dynamically update text in a Label widget, located on a ScriptPane. Naturally, I don't have access to "storage" table in a pane script, so I am trying to pass this data through promise, returned by world.sendEntityMessage(). However, when I try to display promise.result(), I do only get nils. What am I doing wrong?

Notes:

• The object.say in message handler works and displays expected results, so the message is passed to entity
• The promise.error() also returns nil, but promise.succeeded() is false

object .lua file:

Code:

function init()
  storage.MaxCodeLen = 8

  storage.code = storage.code or ""
  storage.screen = storage.screen or ""
  storage.unlocked = false
 
  message.setHandler("add", addChar)
  message.setHandler("enter", enter)
  message.setHandler("erase", delChar)
end

function update(dt)
  object.setAllOutputNodes(storage.unlocked)
 
  -- Automatically lock after timeout.
  if storage.unlocked == true then
    storage.unlocked = false
  end
end

function addChar(msgName, isLocal, char)
  if string.len(storage.screen) < storage.MaxCodeLen then
    storage.screen = storage.screen .. char
  end

  object.say("Current screen: " .. tostring(storage.screen))
  return tostring(storage.screen)
end

function enter(msgName, isLocal)
  if storage.code == "" then -- In setup mode.
    object.say("Password set!")
    storage.code = storage.screen
    storage.unlocked = true
  else                       -- In check mode.
    if storage.code == storage.screen then
      object.say("Password check success!")
      storage.unlocked = true
    end
  end

  storage.screen = "" -- Reset password on exit.
end

function erase(msgName, isLocal)
  if storage.screen ~= "" then
    storage.screen = string.sub(storage.screen, 1, storage.screen.len - 1)
  end
end

interface .lua file:

Code:

function init()
end

function input(char)
  local codeRequest = world.sendEntityMessage(pane.sourceEntity(), "add", tostring(char))
  widget.setText("screen", tostring(codeRequest:result()))
end

function enter()
  world.sendEntityMessage(pane.sourceEntity(), "enter")
end

function backspace()
  world.sendEntityMessage(pane.sourceEntity(), "erase")
end

function num_0()
  input("0")
end

function num_1()
  input("1")
end

-- Etc. for all 9 digits...

 

I think the handlers are not setted right. Here it is an example of some handlers I setted for other mod:

Code:

message.setHandler("getAttributes", function(_, _)
    return getAttributes()
  end)
  message.setHandler("swapAttribute", function(_, _, attribute)
    swapAttribute(attribute)
  end)

I Think that the handler pases two extra arguments besides any argument you send, that's why the two _, .

Edit: Nevermind, I saw that you already have those arguments in your functions. I haven't made things with handlers recently, so I'm not really familiarized with them.

Edit two: Maybe you should be sure that the message have an answer before requesting it. You could made it with something like

Code:

function input(char)
  local codeRequest = world.sendEntityMessage(pane.sourceEntity(), "add", tostring(char))

  local answered = false
  while not answered do
    if codeRequest:finished() then
      widget.setText("screen", tostring(codeRequest:result()))
      answered = true
    end
  end
end

 

Hard to follow code from mobile. Anyhow it is important to understand the messaging is asynchronous. You probably don't get your return right off. That's probably why you get nil. You should have update (or a function called by update) check for results.

edit:
Now that I'm home, I can expand that answer.

Code:

function input(char)
  local codeRequest = world.sendEntityMessage(pane.sourceEntity(), "add", tostring(char))
  widget.setText("screen", tostring(codeRequest:result()))
end

The problem here is expecting a result on the same tic. You need to make the request one time. After that, you call codeRequest:finished() to see if a result is ready, and if it is then codeRequest:result() to retrieve the return from the other entity.

You'll need to save the promise non-locally so that you can access it later. Lets try this instead -

Code:

function init()
  storage.promises = {}
end

function input(char)
  local codeRequest = world.sendEntityMessage(pane.sourceEntity(), "add", tostring(char))
  local p_count = #storage.promises
  storage.promises[p_count + 1] = codeRequest
end

function update(dt)
  local answer
  for i, promise in ipairs(storage.promises) do
    if promise:finished() then
      answer = promise:result()
      table.remove(storage.promises, i)
    end
  end

  if answer then
    widget.setText("screen", tostring(answer))
  end
end

Granted I haven't tested this so errors could exist - especially considering I just typed it into the browser rather than using a decent editor where I can check for obvious mistakes easier. But that should put you on the right track.

You'd need to be sure to define a script delta too, in order to use update()

 

GonDragon, bk3k, thank you for replies. Actually, I thought that asking for result() would force function to wait until result will actually arrive but it seems to not be the case.

GonDragon, as for your suggestion, I don't think that busy waiting is the best option: don't want to hang lua runtime because of some player with bad connection.

bk3k, now I don't really understand the scope of "storage" table. It seems to exist for the whole lifetime of an object, but what about the assotiated ScriptPane? Will storage be cleared when pane is closed?

UPD : The "storage" map is unaccessible in panes. Any other ideas on storing value, so it would be available while panel lives?

UPD2 : Figured it out, just declaring global variable (i.e. without "local") works.

 

Oh didn't realize storage wasn't pre-defined. I'm in the habit of using it because it is already defined in most contexts. Yeah any global would work. No special reason to keep it in storage really. Just a table like any other, with the exception for many things having storage.state - which is actually saved (as boolean only) between sessions. Locals of course only exist in the context they where created and only for the duration of that context.

The ScriptPane I'm pretty sure is going to start from scratch each time you call it anyhow. I believe it only "exists" from the moment you call it, to the moment you close it, so you'd better keep your persistent info in the object(or whatever entity might call it).