[webkit-dev] Easing printf based debugging in WebKit with an helper.

[Alexis Menard]

On Thu, Jul 19, 2012 at 3:01 PM, Oliver Buchtala
<oliver.buchtala at googlemail.com> wrote:
> On 19.07.2012 19:53, Andreas Kling wrote:
>
> On Tue, Jul 10, 2012 at 4:52 PM, Brady Eidson <beidson at apple.com> wrote:
>>
>>
>> On Jul 10, 2012, at 5:25 AM, Alexis Menard <alexis.menard at openbossa.org>
>> wrote:
>>
>> > On Mon, Jul 9, 2012 at 6:53 PM, Brady Eidson <beidson at apple.com> wrote:
>> >>
>> >> On Jul 9, 2012, at 2:43 PM, Alexis Menard <alexis.menard at openbossa.org>
>> >> wrote:
>> >>
>> >>> Hi,
>> >>>
>> >>> For those who "secretly" use printf debugging :). I know the
>> >>> recommended way is to use a debugger and it's not the point of this
>> >>> discussion.
>> >>
>> >> A lot of us do this, and sometimes it's necessary.  I agree with the
>> >> gripe and support adding something easier.
>> >>
>> >>> So I propose wtf() and its stream operator.
>> >>>
>> >>> Usage :
>> >>>
>> >>> wtf()<<"Hello"<<"World"<<3<<4.53322323; will output : Hello World 3
>> >>> 4.53322
>> >>
>> >> There is no reason to bring in stream operators - that are willfully
>> >> absent from WebCore - just for debugging.
>> >>
>> >
>> > But it's really nice for that purpose, and somehow match std::cout
>>
>> And we quite purposefully don't use std::cout in the project.
>>
>> >> Overloading functions works just as well.
>> >
>> > I'm not sure to understand what you mean here…
>>
>> I mean relying on C++'s overloading of functions for the different types
>> you'd like to printf debug.
>>
>> void debug(WebCore::String&);
>> void debug(WebCore::Frame*);
>> void debug(WebCore::Node*);
>>
>> etc etc etc.
>>
>> debug(someFrame);
>> debug(someNode);
>> debug(someString);
>>
>> Especially that last one would help me from remembering how to type
>> "printf("%s", someString.utf8().data())" which is all I've ever really
>> wanted.
>
>
> Hello fellow printfers!
>
> While I'm just as ashamed of my printf habits as the next guy, I think it'd
> be great if we could move forward with this somehow.
>
> Coming from a background in Qt, the stream operator syntax looks perfectly
> normal to me, perhaps you could expand on why we want to avoid using these
> in WebKit. Is there a technical reason, or is it more of a language purity
> issue?
>
> Regardless, adding a consistent set of debug(WebCore::MyCoolOverload)
> methods as suggested would still be massively useful.
>
> -Kling
>
>
> Hi,
>
> I am probably one of those people who much dislike printf-debugging.
> What is your problem with using a debugger?

Say you have a low powered machine that can't link WebKit in debug
even stripped out of SVG etc...

>
> Maybe because the displayed information is not appropriate?
> E.g., you would like
>     someString.utf8().data()
> instead of
>     someString
>
> FWIW, there is a gdb python API for changing the behavior... so called
> pretty printers.
> It is not too difficult to write such pretty-printers.

I think we have some of those.

>
> Maybe providing a set of useful pretty-printers is a better approach than
> providing a set of debug functions?
>
> Regards,
> Oliver
>
>
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>



-- 
Alexis Menard (darktears)
Software Engineer
openBossa @ INdT - Instituto Nokia de Tecnologia