From: James Edward Gray II <james@...>
Date: 2007-11-14T12:16:12+09:00
Subject: Re: recursion with blocks

On Nov 13, 2007, at 9:11 PM, James Edward Gray II wrote:

> On Nov 13, 2007, at 8:54 PM, Raul Parolari wrote:
>
>> James Gray wrote:
>>
>>>
>>> Does this give you some ideas?
>>>
>>> class Tree
>>>    def initialize(name)
>>>      @name   = name
>>>      @leaves = Array.new
>>>    end
>>>
>>>    attr_reader :name
>>>
>>>    def <<(leaf_name)
>>>      @leaves << self.class.new(leaf_name)
>>>      self
>>>    end
>>>    ..
>>
>> I played with this Tree for a while (amazed by its simplicity and
>> functionality); just a small problem when connecting (and printing)
>> Trees to each other. A small touch to the << method does it:
>>
>>  def <<(leaf_name)
>>    case leaf_name
>>       when String
>>         @leaves << self.class.new(leaf_name)
>>       when Tree
>>         @leaves << leaf_name
>>       else raise
>>    end
>>    self
>>  end
>
> Yeah, that's much better.  I actually used a structure close to  
> this, with more niceties of course, for a binary tree I needed.  I  
> was surprised at how easy it was to put together and how flexible  
> it was.  I believe the actual each() method from that one was:
>
>   def each(&block)
>     block[@left] if @left
>     block[self]
>     block[@right] if @right
>   end

Sorry, should have looked it up:

   def each(&block)
     @left.each(&block) if @left
     block[self]
     @right.each(&block) if @right
   end

James Edward Gray II