How can one implement OO in Lua?

Question

Lua does not have build in support for OO, but it allows you to build it yourself. Could you please share some of the ways one can implement OO?

Please write one example

Answer 1

For a quick and dirty oo implementation I do something like -

function newRGB(r,g,b)
  return {
    red=r;
    green=g;
    blue=b;
    name='';
    setName = function(self,name)
      self.name=name;
    end;
    getName = function(self)
      return self.name;
    end;
    tostring = function(self)
      return self.name..' = {'..self.red..','..self.green..','..self.blue..'}'
    end
  }
end

which can then be used like -

blue = newRGB(0,0,255);
blue:setName('blue');

yellow = newRGB(255,255,0);
yellow:setName('yellow');

print(yellow:tostring());
print(blue:tostring());

for a more full featured approach I would use an oo library as was mentioned by eemrevnivek. You can also find a simple class function here which is somewhere between full on library and quick and dirty.