From: Jean-Hugues ROBERT <jean_hugues_robert@...>
Date: 2002-06-18T00:51:06+09:00
Subject: yield and recursion, how to ?



Hello,

I am trying to implement an iterator for a recursive structure. After too much
effort I got:

class Test

   attr_accessor :name
   attr_accessor :children

   def initialize( name )
     @children = []
     @name = name
   end

   def each( block = nil, &syntax_block )
     block ||= syntax_block
     block.call( self, @children.length())
     @children.each do |x|
       x.each block
     end
   end

end

o = Test.new( "Foo")
o.children << Test.new( "Bar")
o.each do |x,y|
   p x.name, y
end

This works OK, but.... this does work as I expected:
def test()
   o.each do |x,y|
     p x.name, y
     break if name == "Foo" # Should break, does not
     return if name == "Foo" # Should return, does not
   end
end
test()

Apparently "break" does not break ("return" does not return) unless some 
"yield" is involved.

However I could not figure out how to rewrite Test##each() using yield.
What am I missing here ?

Thanks,

Jean-Hugues