GTlab Logging

Basic C++14 logging library based on QsLog.

Differences to QsLog

• Removed Qt depdendency. Logging Qt types is still supported, see below.
• Logging of STL types.
• Verbosity levels.
• Custom log destinations using lambdas and functors.
• Full CMake support.

License

GTlab logging is licensed under the 3-Clause BSD License, see LICENSES folder.

Logging Macros:

To log a message use the following macros. They correspond to the six loglevels:

gtTrace()   << "..."; // TraceLevel 
gtDebug()   << "..."; // DebugLevel 
gtInfo()    << "..."; // InfoLevel
gtWarning() << "..."; // WarningLevel 
gtError()   << "..."; // ErrorLevel 
gtFatal()   << "..."; // FatalLevel

Additionally there are six macros, which may be used to set a custom logging id. The id will be logged together with the content:

gtTraceId("...")   << "..."; // TraceLevel 
gtDebugId("...")   << "..."; // DebugLevel 
gtInfoId("...")    << "..."; // InfoLevel
gtWarningId("...") << "..."; // WarningLevel 
gtErrorId("...")   << "..."; // ErrorLevel 
gtFatalId("...")   << "..."; // FatalLevel

In general the output signature looks something like this:

// out: ([ID]) [TIME] <content>

Global Config:

Logging ID:

One may set a global logging by defining the macro GT_MODULE_ID globally.

Qt Support:

The library adds optionally support for Qt types. This must be enabled globally using the define GT_LOG_USE_QT_BINDINGS or by including gt_logging/qt_bindings.h instead.

Additional STL Bindings:

The library adds dedicated logging operators for STL classes like vectors, lists, maps, unique_ptrs etc. These can be included individually e.g. using gt_logging/vector.h. Alternatively they may be included automatically by defining GT_LOG_USE_EXTENDED_STL_BINDINGS globally or by using gt_logging/stl_bindings.h instead.

Local Config:

The logging behaviour may be altered for each file individually:

Log Line Numbers:

One may log line numbers by defining GT_LOG_LINE_NUMBERS before including gt_logging.h. This may be set globally as well.

// out: ([ID]) [TIME] <file>@<lineno>: <content>

Log No Space:

By default this library will log every argument with an trailing space. This can be disabled by defining GT_LOG_NOSPACE before including gt_logging.h. This may be set globally as well.

Log Quotes:

This library can log Qt-String types with quotes. This can be enabled by defining GT_LOG_QUOTE before including gt_logging.h. This may be set globally as well.

Adding an Output Destination:

Note: No output destination is registered by default!

Each destination must be registered using a unqiue id. Destination with the same id will be skipped.

Stdout:

Will log everything to stdout or stderr (only if loglevel >= ErrorLevel).

gt::log::Logger& logger = gt::log::Logger::instance();
logger.addDestination("default", gt::log::makeDebugOutputDestination());

Output:

gtWarning() << "Test";
// out: WARN ([ID]) [10:02:33] Test;

File:

Will log message to the filepath specified. A rotation strategy can be specified.

Functor:

Can be used to forward the output to a function-like object (Functor). The logging behaviour is up to the developer:

static void my_functor(std::string const& message, gt::log::Level level);

// ...

gt::log::Logger& logger = gt::log::Logger::instance();
logger.addDestination("default", gt::log::makeFunctorDestination(my_functor));

Adding an Output Destination at startup:

One may register an logging destination at startup to not miss out on any logging output by invoking a lambda:

static auto init_logger_once = [](){
    gt::log::Logger& logger = gt::log::Logger::instance();
    logger.addDestination("default", gt::log::makeDebugOutputDestination());
    return 0;
}();

Removing an Output Destination:

Output destinations may be removed at any time. A destionation may only be removed by its unique id:

gt::log::Logger& logger = gt::log::Logger::instance();
logger.removeDestination("my_destination");

One may check if a destination exists using gt::log::Logger::hasDestination.