Object Oriented Calls

Code Sharing
1

I have been working at creating a more Object oriented approach to function calls, and I put together this generic object class which can be used to generate subclasses with inheritance from their parent classes. This class comes with internal methods copy(),length(),contains(),keys() and concat(). I am going to add other methods and sub classes as well, but this is what I created so far.

local Test = {"some","test",{"data"},Last = true}

Object:new(Test):keys():concat() – returns list of keys

Object:new(Test):length() – returns 4

Object:new(Test):contains("data") – returns true (deep comparison)

Object:new(Test):copy() – returns object (deep copy)

Sub classes can also be created by passing a table to the Object.new() call and then calling the :new method from the variable returned from the former call. The class will have this new passed table as it’s metatable as well as inheritance of methods from its super class.


Object = {new = false}

------------------------------------------------------------------
-- Primative Object Constructor
------------------------------------------------------------------

function Object:new(obj) -- Generic object constructor 
 local valid = obj and type(obj) == "table"
 local Instance = valid and obj or {}
 setmetatable(Instance,{__index = self}) 
 return Instance
end 
 
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-- Returns the number of elements in an object
function Object:length() 
 local length = 0 for _,_ in pairs(self) do length = length + 1 end
 return length -- Return: "number"
end

-- Returs array object of keys in an object
function Object:keys() 
 local keys = Object:new() for Key,_ in pairs(self) do keys[#keys + 1] = toString(Key) end
 return keys -- Return: "array object"
end

-- Returns true if element exists in object
function Object:contains(element) 
    
    local function Sub_Scan(entry) -- Sub Level Value Comparison
     for _,value in pairs(entry) do
      if value == element then return true
      elseif type(value) == "table" then 
       if Sub_Scan(value) then return true 
    end end end end
    
    local function Scan() -- Top Level Value Comparison
     for _,value in pairs(self) do
      if value == element then return true
      elseif type(value) == "table" then 
       if Sub_Scan(value) then return true end end end
     return false end
    
    return(Scan()) -- Return: "boolean"  
    
end  

-- Returns a deep copy of an object (elements and metatables)
function Object:copy() 
  
  local Clone = {} -- Initial copy container

  local function Sub_Copy(source,target) -- Sub level value copy
   for key,value in pairs(source) do 
    if type(value) ~= "table" then target[key] = value
    else target[key] = {} setmetatable(target[key],getmetatable(source[key])) 
     Sub_Copy(source[key],target[key]) end end end
 
  local function Copy() -- Top Level value copy
    for key,value in pairs(self) do
      if type(value) ~= "table" then Clone[key] = value
      else Clone[key] = {} setmetatable(Clone[key],getmetatable(self[key])) 
       Sub_Copy(self[key],Clone[key]) end end
    setmetatable(Clone,getmetatable(self)) 
   return Clone end
     
 return(Copy()) -- Return: "object"

end

-- Returns concantenated string of array entries
function Object:concat(sep) -- Return: "string"
 if self:length() ~= #self then error("Object.concat only operates on arrays.") end
 return table.concat(self,sep)
end

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2

Wow, this looks really useful and a good learning exercise about classes. Thanks for sharing!

3

My first couple of additions to the object class above are a touch event system which detects multifinger swipe/pinch/spread gestures and a view controler system called by the main draw loop. All elements exist in a 3D plane, and currently a view controller can contain draw cycles which are just functions to be drawn in the controller, or other view controllers. Perspective for all elements inside a view controller are inherited from their parent controller, so you can even have a 3D space within a 3D space infinitely, and each controller would also have it’s own 3D perspective within the 2D plane of its parent controller. Alignment of elements is manual now, but I am working on a layout system similar to the Box layout of Java.

A quick demo of what the controller looks like so far and a couple swipe gestures can be seen in the video below. The view controller system is mostly done, but the gesture recognition will still need work and tuning, as it does not always pick up gestures due to the way it merges swipes into pinches,spreads, or multi-finger gestures.

http://vimeo.com/90710645