> -----Original Message-----
> From: Mark [mailto:[email protected]]
> Sent: Monday, October 14, 2013 5:40 PM
> To: Koehne Kai
> Cc: [email protected]
> 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
Sitz der Gesellschaft: Berlin. USt-IdNr: DE 286 306 868
Registergericht: Amtsgericht Charlottenburg, HRB 144331 B
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