From: Josh Cheek <josh.cheek@...>
Date: 2011-08-01T08:15:46+09:00
Subject: Re: system stack error in ObjectSpace.each_object

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On Sun, Jul 31, 2011 at 4:29 PM, luke gruber <luke.gru@gmail.com> wrote:

> Hey guys, I'm just starting to mess around with metaprogramming in Ruby,
> so I was just having a bit of fun and trying to make a script that would
> allow for creating a 'leader' object in a class, and then when that
> object is sent a message, all other objects of some subordinate class
> would respond to the same message.
>
> So the script I wrote is here:
> https://github.com/luke-gru/lemmings/blob/master/leader.rb
>
> On line 52, I ran into this issue:
>
>  def get_other_objects(subord_class)
>    obj_ary = []
>    ObjectSpace.each_object(subord_class) do |o|
>      obj_ary.push(o) unless o.leader # here
>    end
>    obj_ary
>  end
>
> If I don't have the 'unless o.leader' expression modifier, it pushes
> like a million of the 'leader' objects and raises a SystemStackError.
>
> I have no idea why, and would really appreciate an answer.
>
> Thanks,
>
> -Luke
>
> --
> Posted via http://www.ruby-forum.com/.
>
>

When I ran your script, I didn't get that error. I got this output:


Test
true
#<Test:0x0ac544>
hey guys
hey guys
hey guys
hey guys
hey guys
hey guys
hey guys
hey guys
hey guys
hey guys
hey guys
hey guys
hey guys

#<Test:0x0ac7ec> jumps: 'look at me!'

#<Test:0x0ac5bc> jumps: 'Ahhhhhhhhh!'
#<Test:0x0ac60c> jumps: 'Ahhhhhhhhh!'
#<Test:0x0ac620> jumps: 'Ahhhhhhhhh!'
#<Test:0x0ac634> jumps: 'Ahhhhhhhhh!'
#<Test:0x0ac65c> jumps: 'Ahhhhhhhhh!'
#<Test:0x0ac6c0> jumps: 'Ahhhhhhhhh!'
#<Test:0x0ac710> jumps: 'Ahhhhhhhhh!'
#<Test:0x0ac738> jumps: 'Ahhhhhhhhh!'
#<Test:0x0ac74c> jumps: 'Ahhhhhhhhh!'
#<Test:0x0ac760> jumps: 'Ahhhhhhhhh!'
#<Test:0x0ac788> jumps: 'Ahhhhhhhhh!'
#<Test:0x0ac7ec> jumps: 'Ahhhhhhhhh!'
#<Test:0x0ac544> jumps: 'Ahhhhhhhhh!'

#<Test:0x0ac7ec>
#<Test:0x0ac788>
ouch
ouch
ouch
ouch
ouch
ouch
ouch
ouch
ouch
ouch
ouch
ouch



Typically, SystemStackError is due to recursing for too long, perhaps I have
more memory than you, or perhaps the Ruby I'm using (1.9.2-p180) is less
memory intensive than the one you're using. Anyway, it should give you a
message with more information and a stack trace / line number that tells you
where to begin looking.

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