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Hey all,

i've been banging my head against my desk in fruitless attempts to come up with a good object-oriented menu system in the C++ MUD engine i'm writing.

After going through several C-based MUDs that use an enormous switch statement to handle menus, i'm trying to opt for a cleaner and simpler menu structure. i'm thinking of having a single base class type that can be a menu or an action (i.e. Create New Character or Enter Game, respectively), but i can't seem to get a good design paradigm. Anyone know of any tips or examples for such a process? i keep getting about 90% of the way there, but either a. it gets too complicated or b. it runs into a snag that breaks the whole thing.

Much appreciated!

Each possible action should probably be a class in its own right. Or was that what you meant?

Does this give you any ideas?

class Menu
  def initialize(title, options={})
    @title,@options = title,options
    @selected = nil
  end

  def display
    @options.each do |key,val|
      puts '#{key} - #{val}'
    end
    print '\n>'
  end

  def choose(item)
    if @options[item]
      @selected = item
    else
      raise 'Invalid choice'
    end
  end

  def invoke
    if @selected
      @options[@selected].execute
    else
      raise 'No choice'
    end
  end
end

class Command
   def initialize(name)
     @name = name
   end

   def to_s
     @name
   end

   def execute
     puts 'Command '' + @name + '' executed'
   end
end

menu = Menu.new('My Menu',
   { 1 => Command.new('Foo'),
     2 => Command.new('Bar'),
     3 => Command.new('Baz')})

while true
  begin
    menu.display
    c = $stdin.gets
    menu.choose(c.to_i)
    menu.invoke

  rescue
    puts $!.message
  end

end

(Comment added by Tyche on Tue Sep 27 11:26:33 2005)

By way of translation help....

@variables are instance variables
initialize is a constructor
@options = {} creates an associative array, hash, or map

(Comment added by Tyche on Tue Sep 27 11:55:20 2005)

Whoops! Here's what it looks like executing.

$ ruby menu.rb 
1 - Foo
2 - Bar
3 - Baz

>1
Command 'Foo' executed
1 - Foo
2 - Bar
3 - Baz

>2
Command 'Bar' executed
1 - Foo
2 - Bar
3 - Baz

>5
Invalid choice
1 - Foo
2 - Bar
3 - Baz

>

Consider creating a "parser" class. Have your "session" class support a parser stack so you can "push" and "pop" parser subclasses. Your "session" will simply direct user input to the top parser in the stack.

Now, you can implement each menu in its own subclass of the "parser" class. This minimizes the number of states each "parser" subclass needs to handle. As a user navigates the menu, it may push another "parser" subclass that implements a submenu or "pop" itself to return to the previous menu.

I'm developing something like this now and have a parser subclass identified for each of the following...

account login
character management
in-play
bulletin board
shop
quest conversation

...you get the idea.

-Gromble