Re: [Boost-users] Log: Filter expression in file stream init

Subject: Re: [Boost-users] Log: Filter expression in file stream init
From: Florian Lindner (mailinglists_at_[hidden])
Date: 2015-07-20 04:14:18

Florian Lindner wrote:

> Hello,
> 
> I have this piece of code: http://pastebin.com/iMyyaB6a
> 
> It adds a file and a console log and reads in a file config:
> 
> [Core]
> # Filter="%Severity% > 1"
> 
> [Sinks.MyConsoleSink1]
> Destination=Console
> 
> and prints some messages:
> 
>   using namespace boost::log::trivial;
>   boost::log::sources::severity_logger<severity_level> lg;
>   BOOST_LOG_SEV(lg, trace) << "A trace severity message";
>   BOOST_LOG_SEV(lg, debug) << "A debug severity message";
>   BOOST_LOG_SEV(lg, info) << "An informational severity message";
>   BOOST_LOG_SEV(lg, warning) << "A warning severity message";
>   BOOST_LOG_SEV(lg, error) << "An error severity message";
>   BOOST_LOG_SEV(lg, fatal) << "A fatal severity message";
> 
> It does exactly what I want, prints each message twice to the console. But
> when I uncomment the Filter expression it prints nothing.
> 
> Why not? Severity > 1 means everything info and above, doesn't it?

Ok, it seems in order to use Severity you got to register it before adding 
the sinks:

  boost::log::register_simple_formatter_factory<boost::log::trivial::severity_level, 
char>("Severity");
  boost::log::register_simple_filter_factory<boost::log::trivial::severity_level, 
char>("Severity");

I thought that using the severity_logger is doing that for me. There is a 
bug report related to this https://svn.boost.org/trac/boost/ticket/8840, but 
it was closed for 1.54 and I am on 1.58.

Curious,
Florian