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

[Brady Eidson]

On Jul 25, 2012, at 8:25 AM, Yong Li <yong.li.webkit at gmail.com> wrote:

> 2012/7/19 Brady Eidson <beidson at apple.com>:
>> 
>> On Jul 19, 2012, at 10:53 AM, Andreas Kling <kling at webkit.org> 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?
>> 
>> 
>> A possible technical reason - that I am 100% theorizing about - is that it
>> might bring in more libraries at link time or runtime since it would be the
>> absolute first use of stream operators in the project.
>> 
>> That possibility aside, the stronger part of my objection is language
>> purity.  WebCore uses C++ as "C with classes" and I don't think it's worth
>> it to confuse new (or existing) contributors about that going forward.
>> 
> 
> Can you elaborate why WebCore uses C++ as  "C with classes"?
> 
> We are using namespace, template, operator overloading, virtual
> functions, multi-inheritance, scope object, and even
> pointer-to-member. We prefer Vector<> to C array, and prefer
> OwnPtr/RefPtr to C pointer. Where is C stuff?

I mean we use all the things you just said but we do not use C++ streams.

~Brady