StringBuilder.lua

class "StringBuilder" {
  constructor = function (self,largura,altura)
                  self.elements = {separator = ""}
                end;


  __shl = function (self,value)
            local elements = rawget(self,"elements")
            elements[#elements+1] = tostring(value)
            return #elements
          end;

  __index = function (self,value)
              return self.elements[value]
            end;

  __newindex = function (self,key,value)
                 local elements = rawget(self,"elements")
                 if elements[key] then
                   elements[key] = tostring(value)
                   return
                 end
                 if key == "separator" then
                   elements.separator = tostring(value)
                 end
                 error("Attempt to direct index new items to 'StringBuilder'")
               end;

  __len = function (self,value)
            local elements = rawget(self,"elements")
            return #elements
          end;

  __tostring = function (self)
                 local elements = rawget(self,"elements")
                 local result = ""
                 for i,value in ipairs(elements) do
                   result = result == "" and value or result..elements.separator..value
                 end
                 return result
               end;

  clear = function (self,value)
            local elements = rawget(self,"elements")
            local separator = elements.separator
            rawset(self,"elements",{})
            local elements = rawget(self,"elements")
            elements.separator = separator
          end;

  __idiv = function (self,idx)
             local elements = rawget(self,"elements")
             table.remove(elements,idx)
           end;

  remove = function (self,idx)
             local elements = rawget(self,"elements")
             table.remove(elements,idx)
           end;

  __ipairs = function (self)
               local elements = rawget(self,"elements")
               return ipairs(elements)
             end;

  __pairs = function (self)
               local elements = rawget(self,"elements")
               return ipairs(elements)
             end
  
}

t = StringBuilder:new()
t.separator = "\n"
t << 123
t << 456
t << 789
print(t)