On Tue, Oct 15, 2013 at 10:10 AM, Koehne Kai <kai.koe...@digia.com> wrote:
>
>> -----Original Message-----
>> From: Mark [mailto:mark...@gmail.com]
>> Sent: Monday, October 14, 2013 5:40 PM
>> To: Koehne Kai
>> Cc: development@qt-project.org
>> Subject: Re: [Development] Difficulties using Qt's new categorized logging.
>> How to install filters?
>> [...]
>> Hi Kai,
>>
>> Thank you very much for your explanation! Would you also be able to
>> provide an example for installFilter? Since that is the one where i can't
>> figure
>> out how it's supposed to work.
>
> Sure.
>
> So what you can do is define your own category filter:
>
> QLoggingCategory::CategoryFilter oldCategoryFilter;
>
> void myCategoryFilter(QLoggingCategory *category)
> {
> if (qstrcmp(category->categoryName(), "qt.driver.usb") == 0) {
> category->setEnabled(QtDebugMsg, true);
> } else {
> // let the default filter decide based on text rules
> *oldCategoryFilter(category);
> }
> }
>
> And install it:
>
> oldCategoryFilter = QLoggingCategory::installFilter(myCategoryFilter);
>
>
> inside installFilter() myCategoryFilter will be called for every
> QLoggingCategory object already available. It will also be called whenever a
> new QLoggingCategory object is created, and must be reentrant (might be
> called from multiple threads concurrently).
>
>
> For this specific example you'd be arguably better of just defining a rule by
> setFilterRules. installFilter is mainly useful if you're e.g. defining your
> own logging framework, and say enable/disable categories based on some
> configuration coming from a file, or network ... . It can also be used to
> e.g. log all categories that are created during an application run :)
>
> I'm currently trying to improve the documentation based on your questions,
> please feel free to review:
>
> https://codereview.qt-project.org/#change,68114
>
> Regards
>
> Kai
>
> --
> Kai Köhne, Senior Software Engineer - Digia, Qt
> Digia Germany GmbH, Rudower Chaussee 13, D-12489 Berlin
> Geschäftsführer: Mika Pälsi, Juha Varelius, Anja Wasenius
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Hi Kai,
Now i finally get how it works! But why is it done this way? It just
doesn't smell like the Qt way of doing things. Here is an example of
how i would've expected something like this to work:
QLoggingCategory newCategory("some.new.category");
newCategory->setEnabled(QtDebugMsg, true);
QLoggingCategory::installFilter(newCategory);
Like that or something alike. So why isn't it done like that?
You have to agree with me that this looks a lot cleaner and much more
"the Qt way" then what is currently the situation?
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