WoW:API and scripting quirks

World of Warcraft Scripting Quirks

• Macros
  • Can only cast spells from a hotkey or mouse click
  • Macros cannot cast spells on a delay
  • /cast only works in Macros
  • only one spell or action can be triggered per button press

• Slash Command
  • Can be use single in the Text Mode
  • Can be used in Macros

• Frames
  • OnUpdate handlers are only called when the frame is visible.
  • OnUpdate handles are called every frame. Use with care.
  • When nesting frames, you can access the parent frame name in XML names with with $parent, this is a textual substitution and cannot be used in LUA code. The LUA equivalent to $parent is the GetParent() method of the frame (e.g. getglobal(Frame:GetParent():GetName().."Button") is the same as $parentButton).
  • All Frames have a GetID() function which will obtain the ID specified in the XML. ID's must be positive integers enclosed in quotes: ie. id="1" or id="20"
  • If you don't specify parent="UIParent" in your top-level frames, your frames won't be scaled according to the currently active UI scale. This can lead to some hair-pulling as you try to figure out why your fonts are so huge. (But, in some cases, not having that scaling might be desirable.)
  • If you get no error output, but your addon is simply not being loaded, make sure you don't have a syntax error in your .xml file. A simple way to ensure that your xml is well-formed is to open it in Firefox; it will point out any XML structure errors to you. You can also check the contents of your Logs directory for errors.

• Output to the outside world
  • The only file output allowed is when the UI engine saves variables before it exits or reloads. Addons use the "## SavedVariables:" header to indicate which data they wish to save.
  • Another way to output data is to save certain variables using the SetCVar() function. This will immediatly do an export of the config.wtf file that contains various in game variables. This will not allow you to create new variables to export out, just set non default values to certain in game variables.

• Functions
  • x,y = GetCursorPosition(); will return the current position of the mouse with respect to the object it currently is in. This means x will be 0 if the mouse is at the left edge of a frame or button, regardless of where that frame or button is.
  • x,y = GetCursorPosition(UIParent); will return the current position of the mouse with respect to the entire UI. This can be considered the absolute position..

• ChatFrame
  • Trying to send colored text to other players will cause your client to disconnect. Not sure if Blizz's server is forcing the disconnect, or my client.
    • Example: /tell Name |cFF00FF00Hello|r. The EditBox will show the text in green after replacing "||" with "|". Pressing enter to send the info to the server chat channel results in the following:
      • "|r" causes the disconnect,
      • "|c" doesn't have the same problem, but will cause the text after it not to show.

• Variables
  • If you declare a variable inside an IF block, any attempt to compare the value will fail.
    • In Example 1, "Something" will never print. While in Example 2, "Something" does print.
    • See Talk for more details.

   -- Example 1
   local someVar = true;
   if someVar then
       local someOtherVar = true; -- someOtherVar declared inside an IF block.
   end
   -- someOtherVar *is* set to true at this point, but for some reason the following IF statement ignores it.
   Print(tostring(someOtherVar)); -- "true" is printed.
   if someOtherVar then
       Print("Something"); -- This never gets executed.
   end

   -- Example 2
   local someVar = true;
   local someOtherVar; -- someOtherVar declared before an IF block.
   if someVar then
       someOtherVar = true;
   end
   if someOtherVar then
       Print("Something"); -- This executes as expected.
   end

Also See

• Interface Customization FAQ