[MacRuby-devel] Setting Breakpoints/Debugger

Laurent Sansonetti lsansonetti at apple.com
Thu Jun 18 13:26:14 PDT 2009


I kind-of agree with Eloy here, I almost never use a debugger when  
doing Ruby development (vs when I do C), maybe because the language  
has more higher-level abstractions. The only debugging tool that I use  
is dtrace.

I agree nevertheless that we need a debugger. Ideally we should modify  
the compiler to emit debugging traps that can be used by a regular  
debugger, then we can write an UI for it. But as I wrote earlier this  
isn't something very high on the roadmap for now, because there are  
more high priority things to do. If someone is willing to give this a  
try, he's very welcome, though.

In the meantime you can still more-or-less debug MacRuby code with gdb  
but you need to know about the VM primitives. If you're conformable  
with C this should not be a problem.

Laurent

On Jun 18, 2009, at 12:33 AM, Eloy Duran wrote:

> Hi Pual,
>
> I sometimes use GDB when I need to debug RubyCocoa/MacRuby  
> _themselves_, as they're written in C. For Ruby code, however,  I  
> almost never need a debugger.
> Maybe it's because I write most code test driven so I know that the  
> code is probably ok when I actually use it. In the cases where it  
> didn't pan out as expected, I use print style debugging or ruby- 
> debug (RubyCocoa). For a more elaborate explanation, please see the  
> testing video of Manfred explaining about it at the Ruby on OS X  
> conference: http://www.fngtps.com/2009/06/ruby-on-os-x-conference-videos
>
> We have a fairly big RubyCocoa app and some of our Rails apps are  
> really big.
>
> It's unfortunate that ruby-debug doesn't work on MacRuby, but  
> Laurent has already announced that at some point in the future work  
> will be done in this area. But at this moment, MacRuby itself still  
> needs lots of work. So we'll need to have a bit more patience for a  
> real debugger.
>
> HTH,
> Eloy
>
> On Jun 18, 2009, at 4:42 AM, Paul Howson wrote:
>
>> On 04/06/2009, at 6:57 AM, Laurent Sansonetti wrote:
>>
>>> I have an idea about adding facilities inside the new VM in order  
>>> to attach a debugger to it (and we could even patch gdb to add  
>>> Ruby support!) but I won't be able to start this any time soon,  
>>> because there are too many higher priority things to implement  
>>> first. But if one wants to help... patches are always welcome.
>>>
>>> Laurent
>>
>> Hmmm. Lack of debugger support is surely a serious limitation. A  
>> deal-stopper for any complex real-world app I would have thought.
>>
>> I guess you're aware that this will eventually be needed.
>>
>> Is anyone using MacRuby for a large project? How are they coping  
>> without a debugger? (I'd like to know since I'm planning to convert  
>> an old non-Objective-C app to MacRuby).
>>
>> Paul Howson
>> Queensland Australia
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>
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