4 // Fraunhofer Institute for Open Communication Systems (FOKUS)
5 // Competence Center NETwork research (NET), St. Augustin, GERMANY
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.
24 \brief Log public header */
26 #ifndef HH_SENF_Utils_Logger_Log_
27 #define HH_SENF_Utils_Logger_Log_ 1
30 #include <boost/preprocessor/seq/size.hpp>
31 #include <boost/preprocessor/dec.hpp>
32 #include <boost/preprocessor/seq/elem.hpp>
33 #include <boost/preprocessor/seq/pop_back.hpp>
34 #include "Parameters.hh"
38 ///////////////////////////////hh.p////////////////////////////////////////
40 /** \defgroup logging Logging commands
42 The logging library provides several commands to create %log messages. All these macro commands
43 take a variable number of arguments. Since this is not supported in a usable way by the C++
44 preprocessor, the arguments are encoded into a <a
45 href="http://www.boost.org/libs/preprocessor/doc/index.html">Boost.Preprocessor</a> like
49 SENF_LOG( (senf::log::Debug)(senf::log::NOTICE)(FroblizerArea)("The log message") );
52 The argument is comprised of a sequence of parameters and the %log message itself.
54 - the <em>%log stream</em>,
55 - the <em>%log area</em>,
56 - the <em>%log level</em>.
58 These parameters are optional and may be specified <i>in arbitrary order</i> (with the %log
59 message always being the last sequence element) and even multiple times in the parameter
60 sequence. If some argument type occurs multiple times, the last occurrence wins. If any one of
61 the parameters is not specified, it's current default value will be used.
63 This current default value is set using \ref SENF_LOG_DEFAULT_STREAM, \ref SENF_LOG_DEFAULT_AREA
64 and \ref SENF_LOG_DEFAULT_LEVEL respectively. These macros set the default stream, area and/or
65 level <em>of the current scope</em>. They may be used with a class declaration to set defaults
66 for all class members or within a function or member body to set the default for that member
67 only. They may be used only \e once within each scope.
69 The logging library defines the global defaults for stream, area and level to be \c
70 senf::log::Debug, senf::log::DefaultArea, and senf::log::NONE respectively.
72 The %log level senf::log::NONE is special. If the %log level is set to this value, the %log level
73 will be set from the stream provided default value.
75 All these parameters must be <em>compile time constants</em> (they are all types, so it's
76 difficult for them to be something else).
78 \section logging_aliases Aliases
80 To further simplify logging commands, aliases may be defined within any scope. An alias is an
81 arbitrary collection of %log parameters:
83 SENF_LOG_DEFINE_ALIAS( VerboseDebug, (senf::log::Debug)(senf::log::VERBOSE) );
85 Within %log statements, aliases may be used like normal parameters. They will be substituted for
86 the parameter sequence they represent:
88 SENF_LOG( (VerboseDebug)("Debug message") )
90 SENF_LOG( (senf::log::Debug)(senf::log::VERBOSE)("Debug message") )
92 Aliases may be used together with other parameters, even with further aliases in any order.
95 ///\addtogroup logging
98 ///\name Generating log messages
101 /** \brief Write log message
103 This macro will write it's last argument to the log stream. The last argument must be an
104 expression which will be placed after a streaming \c operator<< (like
105 <i>some-log-stream</i> \c << <i>last-macro-arg</i>).
107 SENF_LOG((parameters...)("log message " << args << ...));
112 #define SENF_LOG(args) \
113 SENF_LOG_BLOCK_( SENF_LOG_MERGE_PARAMETERS(BOOST_PP_SEQ_POP_BACK(args)), \
114 { log << BOOST_PP_SEQ_ELEM(BOOST_PP_DEC(BOOST_PP_SEQ_SIZE(args)),args); })
116 /** \brief Write log message (template context)
118 This macro is used like \ref SENF_LOG() if called from a template context
122 #define SENF_LOG_TPL(args) \
123 SENF_LOG_BLOCK_( SENF_LOG_MERGE_PARAMETERS_TPL(BOOST_PP_SEQ_POP_BACK(args)), \
124 { log << BOOST_PP_SEQ_ELEM(BOOST_PP_DEC(BOOST_PP_SEQ_SIZE(args)),args); })
126 /** \brief Enable block based on logging parameters
128 This macro is like SENF_LOG, however instead of writing a simple message, this macro allows
129 to specify a complete block of code to be executed if the log message is enabled.
131 SENF_LOG_BLOCK((parameters...)({
132 // arbitrary code using 'log' for logging
133 log << "log message";
139 #define SENF_LOG_BLOCK(args) \
140 SENF_LOG_BLOCK_( SENF_LOG_MERGE_PARAMETERS(BOOST_PP_SEQ_POP_BACK(args)), \
141 BOOST_PP_SEQ_ELEM(BOOST_PP_DEC(BOOST_PP_SEQ_SIZE(args)),args))
143 /** \brief Write log message (template context)
145 This macro is used like \ref SENF_LOG_BLOCK() if called from a template context
149 #define SENF_LOG_BLOCK_TPL(args) \
150 SENF_LOG_BLOCK_TPL_( SENF_LOG_MERGE_PARAMETERS_TPL(BOOST_PP_SEQ_POP_BACK(args)), \
151 BOOST_PP_SEQ_ELEM(BOOST_PP_DEC(BOOST_PP_SEQ_SIZE(args)),args))
156 ///////////////////////////////hh.e////////////////////////////////////////
166 // comment-column: 40
167 // c-file-style: "senf"
168 // indent-tabs-mode: nil
169 // ispell-local-dictionary: "american"
170 // compile-command: "scons -u test"