From: ptkwt@...1.aracnet.com (Phil Tomson)
Date: 2002-10-30T05:35:30+09:00
Subject: Re: problem with recursive structure

In article <5.1.0.14.2.20021029141528.00b146e8@zcard04k.ca.nortel.com>,
Mark Probert  <probertm@nortelnetworks.com> wrote:
>
>Dear Rubists,
>
>I have a little class called SimpleTree that makes a recursive
>data structure of arrays.  I am getting some funny behaviour when
>I traverse the tree for printing.
>
>The print routine is:
>
>     def pp_branch(b)
>         puts "(head) #{b[0]}"
>         b.each { |item|
>             next if item == b[0]        # avoid the head
>             pp_branch(item) if item.type == Array
>             puts "(leaf) #{item}"
>         }
>     end
>
>Output looks like:
>
>["a", "b", ["z/", "a", "b", ["y/", "c", "d"], "e"]]
>(leaf) a
>(leaf) b
>(head) z/
>(leaf) a
>(leaf) b
>(head) y/
>(leaf) c
>(leaf) d
>(leaf) y/cd
>(leaf) e
>
>It is the line "y/cd" that gets me.  Ruby (or is it me?) appears
>to be flattening included array "y".
>
>Anyone help me with this?
>TIA,
>

I don't really have an answer for you, but I get something slightly 
different(but still wrong) when I run this in 1.6.7:

(head) a
(leaf) b
(head) z/
(leaf) a
(leaf) b
(head) y/
(leaf) c
(leaf) d
(leaf) y/cd
(leaf) e
(leaf) z/aby/cde  <------

note the last line is in addition to what you had.

I ran this in the debugger and it seems that at the end of a sub-array it 
prints the while sub-array as a leaf.  I couldn't figure out why it was 
doing this.  What version of Ruby are you running?  

Phil