From: Robert Klemme <bob.news@...>
Date: 2005-07-01T16:55:43+09:00
Subject: Re: debugger issue

pat eyler wrote:
> I'm running into an unexpected issue with the debugger, and I'm
> hoping someone here can help me out.  I' ve got a short program like
> this (stolen directly from zenspider's RubyInline tutorial):
>
> -=-=-=-=-=-=-=-=-=-=-=-=-=-==-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> #!/usr/local/bin/ruby -w
>
> class Array
>
>   def average
>     result = 0
>     self.each { |x| result += x }
>     result / self.size.to_f
>   end
>
> end
>
> max_loop = (ARGV.shift || 5).to_i
> max_size = (ARGV.shift || 100_000).to_i
> a = (1..max_size).to_a
>
> 1.upto(max_loop) do
>   avg = a.average
>   $stderr.print "."
> end
> $stderr.puts ""
> -=-=-=-=-=-=-=-=-=-=-=-=-=-==-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>
>
> Everytime I step to line 7 (the self.each ... line) or do a step nnn
> which executes line 7, the debugger stops there.  Neither step or
> next will move past this line.  If I try to continue the program, it
> will run to the next breakpoint or end of the program.
>
>
> -=-=-=-=-=-=-=-=-=-=-=-=-=-==-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> pate@linux:~/scripts> ruby -rdebug averager.rb
> Debug.rb
> Emacs support available.
>
> averager.rb:3:class Array
> (rdb:1) s 13
> averager.rb:7:    self.each { |x| result += x }
> (rdb:1) s
> averager.rb:7:    self.each { |x| result += x }
> (rdb:1) s
> averager.rb:7:    self.each { |x| result += x }
> (rdb:1) s
> averager.rb:7:    self.each { |x| result += x }
> (rdb:1) n
> averager.rb:7:    self.each { |x| result += x }
> (rdb:1) n
> averager.rb:7:    self.each { |x| result += x }
> (rdb:1) n
> averager.rb:7:    self.each { |x| result += x }
> (rdb:1) n 20
> averager.rb:7:    self.each { |x| result += x }
> (rdb:1) c
> ....
> pate@linux:~/scripts>
> -=-=-=-=-=-=-=-=-=-=-=-=-=-==-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>
>
> Any idea what's going on?  Is this a bug in the debugger, or am I
> misunderstanding something?

My guess would be that Array#each is a method implemented in C and that
your block is just a single line block.  The debugger can't step into
Array#each and maybe it cannot stop in the block because it's on the same
line.  Did you try to convert the block to a multiline block?

If you step over that line then you execute a single each call, which
happens to execute multple callbacks of the block.

Kind regards

    robert