From: Eero Saynatkari <eero.saynatkari@...>
Date: 2006-09-09T08:46:20+09:00
Subject: Re: Puzzling bug with yielded array

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



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