[fxruby-users] Inheritance

Joel VanderWerf vjoel at path.berkeley.edu
Thu Feb 9 14:58:31 EST 2006


Uwe Hartl wrote:
> Hi,
> I want to create an object from data I have no idea which type it is. Assuming 
> I have the possibilities to have an date and an int. Now I want to create 
> from both an object that has the the same capabilities (e.g. show itself in a 
> parent FXFrame). But there should be specific things for the different data 
> types to be modified (the textfield for the int should just allow numbers and 
> the textfield of the date should allow numbers and ":" and there should be a 
> button beside it which pops up a FXCalendar Dialog). what I want is basically 
> to create a class (lets call it Data), which has a constructor which figures 
> out from which class (DateVis or IntVis) itself should inherit. Something 
> like this:
> 
> class Data
> 	def initialize(d)
> 		if d.class == "Fixnum"
> 			inherit from IntVis
> 		elsif d.class == "Date"
> 			inherit from DateVis
> 		end
> 	end
> end 
> 
> I don't get it done. Does anybody have a clue if this is possible? Kind of 
> inheritance after the fact of creation?
> 
> Thanks
> Uwe
> 

Two suggestions:

1) use modules and extend. Replace "inherit from IntVis" with

     d.extend IntVis

2) use a "factory" class and some subclasses:

     class Data
       def self.new_from_value(d)
         case value
         when Fixnum; DataFixNum.new
         when Date; ....
       end
     end

-- 
        vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407


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