[Boost-users] Boost.Log - textual format with severity

Subject: [Boost-users] Boost.Log - textual format with severity
From: Keith Bennett (keithb_at_[hidden])
Date: 2014-05-12 12:04:20

Hello! I'm new to boost log (like many others, I imagine since it's only a
relatively new library).

I'm trying to specify a format textually (eg, keywords::format =
"blahblah", instead of using a compiled expression). The idea is that the
format can be reconfigured easily either through a command line parameter
or through the configuration file without needing to recompile.

However, it seems that anything specifying %Severity% when using a custom
severity_level enum will simply not be output at all.

Take the example from libs/log/example/keywords/main.cpp

Simply changing line 86 to be:
    logging::add_console_log(std::clog, keywords::format = "%Severity%
%TimeStamp%: %_%");

will exhibit the problem I believe I am trying to resolve.

My suspicion is that the core doesn't know about the custom Severity
attribute because it hasn't been registered and so is unable to parse
%Severity% to any formatter. In contrast, the add_file_log below that does
correctly output the severity level because it uses a compiled expression
and is therefore able to deduce what needs to be done (am I correct in that
assumption)?

I seem to be unable to add an attribute to resolve this without rolling my
own attribute class. How do I add an attribute or formatter related to the
Severity which was declared with BOOST_LOG_ATTRIBUTE_KEYWORD?

I think it's worth noting that if I remove the template parameter to
severity_logger on line 123 so that it matches thus:
    src::severity_logger< > slg;

It then devolves into a standard int instead of an enum and the output is
"correctly" seen -- as an int and not as a human-readable string. While
this is okay for now, I would of course want it to be human-readable if
possible. This is as it is in the example in
libs/log/example/settings_file/main.cpp.

Any help would be appreciated.

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