sysrap/tests/sLOG_MACRO_Test.cc

0001 /*
0002  * Copyright (c) 2019 Opticks Team. All Rights Reserved.
0003  *
0004  * This file is part of Opticks
0005  * (see https://bitbucket.org/simoncblyth/opticks).
0006  *
0007  * Licensed under the Apache License, Version 2.0 (the "License");
0008  * you may not use this file except in compliance with the License.
0009  * You may obtain a copy of the License at
0010  *
0011  *   http://www.apache.org/licenses/LICENSE-2.0
0012  *
0013  * Unless required by applicable law or agreed to in writing, software
0014  * distributed under the License is distributed on an "AS IS" BASIS,
0015  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
0016  * See the License for the specific language governing permissions and
0017  * limitations under the License.
0018  */
0019
0020 #include <cassert>
0021 #include "SLOG.hh"
0022 #include "SArgs.hh"
0023
0024 #include "SYSRAP_LOG.hh"
0025
0026
0027 int main(int argc, char** argv)
0028 {
0029     SLOG_(argc, argv);
0030     SYSRAP_LOG__ ;
0031
0032     plog::Severity level = info ;
0033
0034     sLOG(level, -3) << "-3" ;
0035     sLOG(level, -2) << "-2" ;
0036     sLOG(level, -1) << "-1" ;
0037     sLOG(level, 0) << "0" ;
0038     sLOG(level, 1) << "1" ;
0039     sLOG(level, 2) << "2" ;
0040     sLOG(level, 3) << "3" ;
0041
0042
0043
0044     std::cout << R"(
0045
0046
0047     Use sLOG(level, delta) to adjust logging level
0048     required for the output of the message relative to a base level.
0049     Note the inversion as are changing the level to get an output:
0050
0051        -ve : message will appear *more*
0052        +ve : message will appear *less*
0053
0054     This allows a base severity level to be set for a class,
0055     with some delta variations off that.
0056
0057     Usage::
0058
0059        plog::Severity m_level = info ;  //  typically class member with base severity
0060
0061        sLOG(m_level, -1) << "Decrease needed log level below base : so will appear more " ;
0062        sLOG(m_level,  0) << "Leave loglevel asis, same as LOG(m_level) << ... " ;
0063        sLOG(m_level, +1) << "Increase needed log level above base : so will appear less " ;
0064
0065
0066     This avoids manual adjustment of lots of output levels, whilst debugging a class
0067     up the base by fixing m_level eg m_level(info) and establish an output level
0068     structure :
0069
0070     * logging inside loops should have +1/+2 relative to base
0071     * infrequent high level flow output -2/-1 so they appear usually
0072
0073     Then once the class is behaving dial down m_level, to reduce output while
0074     still leaving the high level flow visible.
0075
0076     You can also of course change the cut, which adjusts all levels for the
0077     entire package not just the class being debugged:
0078
0079        OKX4Test --cfg4 debug
0080        OKX4Test --cfg4 warning
0081
0082
0083     To shut a class up set m_level(verbose) then only -2s will appear with
0084     default level of info
0085
0086
0087
0088
0089     Note the limited range::
0090
0091     enum Severity
0092     {
0093         none = 0,
0094         fatal = 1,
0095         error = 2,
0096         warning = 3,
0097         info = 4,
0098         debug = 5,
0099         verbose = 6
0100     };
0101
0102 )" ;
0103
0104
0105     return 0 ;
0106 }
0107
0108