4 // Fraunhofer Institut fuer offene Kommunikationssysteme (FOKUS)
5 // Kompetenzzentrum fuer Satelitenkommunikation (SatCom)
6 // Stefan Bund <g0dil@berlios.de>
8 // This program is free software; you can redistribute it and/or modify
9 // it under the terms of the GNU General Public License as published by
10 // the Free Software Foundation; either version 2 of the License, or
11 // (at your option) any later version.
13 // This program is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the
20 // Free Software Foundation, Inc.,
21 // 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
23 /** \mainpage The SENF Logging library
25 The Loggger infrastructure implements a highly flexible compile- and run-time configurable
26 logging infrastructure supporting multiple streams, user definable log areas and fine grained
27 log levels. Logging can be configured at compile and runtime on any combination of above
28 parameters. The library supports a host of log targets and messages can be routed into multiple
29 targets at the same time. To allow concise usage of the library, a utility to define logging
30 defaults for any scope is provided.
32 An important basic concept of the library is, that most of the macros take a variable number of
33 arguments. Since this is not supported in the needed manner by the C++ preprocessor, the
34 arguments are encoded into a <a
35 href="http://www.boost.org/libs/preprocessor/doc/index.html">Boost.Preprocessor</a> like
39 SENF_LOG( (senf::log::Debug)(senf::log::NOTICE)(FroblizerArea)("The log message") );
42 The last sequence element always is the log message. Before that we have a number of log
43 parameters <i>in arbitrary order</i>. Since giving all the parameters in every log message is to
44 verbose, there are two helpful constructs to reduce the verbosity. Using \ref
45 SENF_LOG_DEFAULT_STREAM, \ref SENF_LOG_DEFAULT_AREA and \ref SENF_LOG_DEFAULT_LEVEL it is
46 possible to define the default logging parameters to be used within a given scope. Using \ref
47 SENF_LOG_DEF_ALIAS you can define an alias (which is a scoped symbol) as an arbitrary
48 combination of parameters.
51 SENF_LOG_DEF_STREAM( userLog, senf::log::MESSAGE, senf::log::MESSAGE );
55 // Define a new log area
56 SENF_LOG_DEF_AREA(FroblizerArea);
58 // Set default log parameters for this scope
59 SENF_LOG_DEFAULTS((senf::log::Debug)(senf::log::NOTICE)(FroblizerArea));
61 // Define an alias for emergency messages to the sysadmin.
62 // The log area is inherited from the default at the place, where this
63 // alias is used *not* where it is defined
64 SENF_LOG_DEF_ALIAS(LogEmerg, (userLog)(senf::log::CRITICAL));
72 void Froblizer::froblize()
74 SENF_LOG(("This is the Debug stream at level NOTICE in the FroblizeArea"));
75 SENF_LOG((senf::log::WARNING) ("Same stream and area but at warning level"));
76 SENF_LOG((LogEmerg) ("This goes to the userLog at level CRITICAL in the FroblizerArea"));
79 void Froblizer::test()
81 // Change the default log level for this method. stream and area are taken
82 // from the next scope up
83 SENF_LOG_DEFAULTS((senf::log::VERBOSE));
85 SENF_LOG(("Log to Debug stream in Froblizer area however at VERBOSE level"));
89 Currently, the library is not implemented in any way. The interface has been defined up to a
90 point and we have dummy implementations of the 'in-code' part of the interface. This is the
91 part, which is called throughout the code. The configuration API is defined but we don't even
92 have a template implementation. However, this allows starting to use the SENF Logger in newly
93 developed code. Even though this code will unconditionally log everything to \c std::cerr for
94 now and errors in the parameter specification will not be caught (since they are just ignored)
95 the logging should work automatically as advertised as soon as the logger is completely
98 I did not find any implementation which was not either completely convoluted, unusable or
99 slow. So I turned to a macro based implementation which can provide all the design goals stated
102 \section logger_compile_conf Compile time configuration
104 The logger infrastructure allows to enable or disable log levels or areas at compile
105 time. Levels or areas disabled at compile time do not generate any code. The compile time
106 configuration is done in two parts: When defining log streams, default log levels and log level
107 limits are defined. Additionally the \c SENF_LOG_CONF symbol can be defined to customize this
108 default configuration.
110 The \c SENF_LOG_CONF symbol is a Boost.Preprocessor style sequence of sequences:
112 g++ ... -DSENF_LOG_CONF="((senf::log::Debug)(_)(DISABLED)) \
113 ((senf::log::Debug)(foo::FooArea)(VERBOSE))" ...
115 Each element defines the compile time limit for a stream and optional area.
117 \implementation I would have much preferred a more C++ like implementation. However given the
119 \li Flexible configuration at compile and runtime
120 \li Concise usage and simple interface
121 \li Zero overhead for compile-time disabled log messages
128 // comment-column: 40
129 // c-file-style: "senf"
130 // indent-tabs-mode: nil
131 // ispell-local-dictionary: "american"
132 // compile-command: "scons -u test"