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Default values not working?? — Gideros Forum
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    Default values not working??

    antixantix Member
    edited August 2015 in General questions
    Hey all. I am setting up an actor in my game engine with a table of options but something is not quite working when I go to set a default property if the option is missing from the table....
    local function addActor1(options)
  local actor = {}
  actor.shrinks = options.shrinks or false
  print(actor.shrinks)
end
 
local function addActor2(options)
  local actor = {}
  actor.shrinks = options.shrinks or true
  print(actor.shrinks)
end
    Calling either function with a blank table for options works fine. If I call addActor1({shrinks = true}), then actor.shrinks is TRUE as I would expect. If I call the addActor2({shrinks = false}) however, actor.shrinks is still TRUE! Why is it not false?

    I thought if shrink has been specified then that value would be used, and if shrink was not specified then the default TRUE would be used.

    Am I missing something simple here (as per usual)??
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    Comments

    • ar2rsawseenar2rsawseen Maintainer
      @antix problem is that or is a boolean expression
      and what you are doing is evaluating

      false or true, which will always be true.

      You can do such default value assignment but, not with booleans (or probably even not numbers)

      you would need to explicitly check if it is nil
      if options.shrink == nil then
    options.shrink = true
end
      http://appcodingeasy.com/Gideros-Mobile
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    • FyfffFyfff Member
      edited August 2015 Accepted Answer
      Man, you set "shrinks = false" so when Lua check the condition with "or" it think that the first argument == false and then return the second argument (it's a rule of "or" expression). You've better use another flag, like "0" or string "false".

      Oh, you also can use that
      actor.shrinks = true and options.shrinks
      mad, but valid
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    • antixantix Member
      @ar2rsawseen thanks. I am having success with numbers though :)

      @Fyfff awesome, I'll use that since it's less code :)
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    • FyfffFyfff Member
      @antix
      Btw, this code will return "nil" if you don't set the "shrinks" field explicitly. If you want to have "true" when "shrinks" doesn't set you need smth like this:
      actor.shrinks = true and (options.shrinks == nil or options.shrinks)
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    • antixantix Member
      @Fyfff ahh okay cheers. Its all working now and I can move on from particle systems to something interesting like animation systems *yawn* :))
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