From: John Morrice <spoon@...>
Date: 2010-11-18T21:08:59+09:00
Subject: Re: Ruby Not observing DRY principle


> > I don't really understand what you're trying to do there, but I
> > think you need:
> >
> > - An event handler (to intercept user input)
> > - Blocks to handle each of your events
> > - The process itself (a class representing what the program does)
> > ** And, if the user is calling algorithms, then each algorithm
> > belongs to it's own class/function.  How you call them is a matter
> > of taste (I would push a hash with algorithm parameters).

That is an example of the strategy pattern!

http://www.c2.com/cgi/wiki?StrategyPattern

> option1
>         foo(set of variables, user input 1)
>         # set of variables will be different for each option
>         # Sets will have same variable types but different values
> option 2
>         foo(set of variables, user input 1)
>         foo(set of variables, user input 2)
> option 3
>         foo(set of variables, user input 1)
>         foo(set of variables, user input 2)
> option 4
>         foo(set of variables, user input 1)
>         foo(set of variables, user input 2)

Is this sort of thing what you mean?

# The main loop
def main
   loop do
      puts "Please choose an option:"
      puts " [1] Option1"
      puts " [2] Option2"
      puts " [3] Option3"
      opt = nil

      # A primitive event handler
      case gets.to_i
      when 1
         opt = Option1.new
      when 2
         opt = Option2.new
      when 3
         opt = Option3.new
      end

      # Check if a valid option was entered
      if opt
         opt.run
      else
         puts "Error: please enter valid option."
      end
   end
end

# Run the program
main

You also need to define

# The first option.  I wish I had a better name!
class Option1

   # get some details
   # send to file dated with date user supplied
   # send to database
   def run
   end

end

Flebber, the benefit of using objects to represent your options, rather
than just functions, is that you may then apply the various object
oriented techniques.

E.g. TemplateMethod could remove duplicate code from
similar Options

http://www.c2.com/cgi/wiki?TemplateMethod

However, using a strict object oriented approach can be pretty
heavy-weight!

Johnny