From: "A. S. Bradbury" <asbradbury@...>
Date: 2006-09-09T19:46:46+09:00
Subject: Re: Puzzling bug with yielded array

On Saturday 09 September 2006 00:46, Eero Saynatkari wrote:
> Rick Denatale wrote:
> > On 9/8/06, A. S. Bradbury <asbradbury@tekcentral.org> wrote:
> >> A more general question - how would you (ruby-talk readers) implement
> >> this method? Two people on #ruby-lang suggested I make it recursive, but
> >> I really don't see this sort of tree traversal mapping to a recursive
> >> method, am I wrong?
> >
> > Tree traversal usually lends itself well to a recursive
> > implementation, but it's not clear to me exactly what your each_level
> > method is supposed to do.
> >
> >
> > But here's a recursive implementation that might do the same thing.
> >
> > def each_level(include_self=false, &block)
> >       yield [self] if include_self
> >       kids = children.values
> >       unless kids.empty?
> >            yield kids
> >            kids.each do {|kid| kid.each_level(&block)}
> >       end
> > end
>
> That is a semi-depth-first traversal, though. Apparently
> we are looking for breadth-first here :) That would be
> simplest to implement with some kind of a storage--say
> an Array with an element for each level--which is sort
> of what the OP's method was doing (though only for the
> first three levels since it does not recurse).
>
> > Rick DeNatale

Indeed, I am implementing a breadth-first or level-by-level traversal. I don't 
understand your comment about "only for the first three levels"?

I can see other forms of tree traversal lending themselves well to a recursive 
implementation, but not really level by level, particular as I want each 
level to be returned as an array. 

Alex