From: Alex Chaffee <alex@...>
Date: 2012-07-06T13:00:11+09:00
Subject: Re: Using binding + set trace func to capture execution state

Nice timing! For kicks, I just wrote a gem that emulates Java's
behavior of printing stack traces when you hit ctrl-backslash. (The
idea is to debug programs that are stuck in an infinite loop or
something somewhere.) I tried to also print local and instance
variables but hit a wall; this may help with that.

It's not really ready for prime time but you can check it out:
http://github.com/alexch/thready

 - A

On Wed, Jul 4, 2012 at 1:49 AM, Robert Klemme
<shortcutter@googlemail.com> wrote:
> On Wed, Jul 4, 2012 at 9:57 AM, Bartosz Dziewoński <matma.rex@gmail.com> wrote:
>> You can use the `local_variables` method to get a list of local
>> variables in current scope. So maybe something like this:
>>
>> $values_at_time = {}
>>
>> set_trace_func proc { |event, file, line, id, binding, classname|
>>         if event == "line"
>>                 $values_at_time[line] = binding.eval('local_variables.map{|v| [v,
>> eval(v.to_s)] }')
>>         end
>> }
>>
>> a = 5
>> stuff = 'asd'
>> a += 8
>>
>> set_trace_func nil
>> pp $values_at_time
>
> That still suffers from the issue of changes in referenced object
> which will modify the stored state.  Even adding to an Array will
> change history.  As I said earlier you would need to store a complete
> object graph, something like
>
> $values_at_time = {}
>
> set_trace_func proc { |event, file, line, id, binding, classname|
>         if event == "line"
>                 $values_at_time[line] =
> Marshal.dump(binding.eval("local_variables").inject({})
> {|h,v|h[v]=binding.eval(v.to_s);h})
>         end
> }
>
> Kind regards
>
> robert
>
> --
> remember.guy do |as, often| as.you_can - without end
> http://blog.rubybestpractices.com/
>



-- 
Alex Chaffee - alex@stinky.com
http://alexchaffee.com
http://twitter.com/alexch