From: Charles Lowe <aquasync@...>
Date: 2007-11-08T07:53:32+09:00
Subject: Re: instantiating random sub-classes (Dragon, TeethDeer, etc

Thufir wrote:
> In Driver, I was considering creating a pseudo-random number between 0
> and 4, then using case:
> 
> case 0
> AssistantViceTentacleAndOmbudsman
> 
> case 1
> Dragon
> 
> case 2
> DwarvenAngel
> 
> case 3
> IntrepidDecomposedCyclist
> 
> case 4
> TeethDeer
> 
> 
> so that the array of Creatures is filled with a variety of monsters
> which inherit from Creature.  However, there's gotta be another way.
> Perhaps ask Creature what its sub-classes are?  Then randomly select
> from that list/array of monsters?
> 
> Here's the code:
> 
> C:\code>
> C:\code>type Driver.rb
> require 'ArrayOfCreatures'
> require 'Dragon'                                      #Dragon inherits
> from Creature
> require 'Creature'                                    #Subclasses
> include:  Dragon, TeethDeer, etc
> 
> #numOfCreatures=Kernel.rand(3)
> 
> puts "\nquantity of creatures:"
> numOfCreatures = gets.chomp.to_i
> 
> 
> someCreatures = ArrayOfCreatures.new
> 
> 
> 0.upto(numOfCreatures) do |i|
>         someCreatures[i]=Dragon.new              #what about other
> types (children/sub-classes) of creature?
>         print "\n"
>         print "someCreatures["
>         print i
>         print "]:\n"
>         print someCreatures[i].toString
> end
> 
> 
> C:\code>
> 
> 
> thanks,
> 
> Thufir

There are two ways to get a list of subclasses. One is to use 
ObjectSpace#each_object, which is kind of messy, and the other is to use 
the Creature.inherited hook, to build up the array.

Alternatively, and to add more flexibilty, you could add a creature 
weights hash. Eg something like:

class Creature
  WEIGHTS = {}
end

class Dragon < Creature
  WEIGHTS[self] = 0.5
end

class SomeScaryGuy < Creature
  WEIGHTS[self] = 0.25
end

(Doesn't matter if they don't add to one)

Or make the weights be dependent on some difficulty setting....
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