GSW_AI_LAB/carl/doc/markdown/developers/logging.md

Logging

Logging frontend

The frontend for logging is defined in [logging.h](@ref logging.h).

It provides the following macros for logging:

• LOGMSG_TRACE(channel, msg)
• LOGMSG_DEBUG(channel, msg)
• LOGMSG_INFO(channel, msg)
• LOGMSG_WARN(channel, msg)
• LOGMSG_ERROR(channel, msg)
• LOGMSG_FATAL(channel, msg)
• LOG_FUNC(channel, args)
• LOG_FUNC(channel, args, msg)
• LOG_ASSERT(channel, condition, msg)
• LOG_NOTIMPLEMENTED()
• LOG_INEFFICIENT()

Where the arguments mean the following:

• channel: A string describing the context. For example "carl.core".
• msg: The actual message as an expression that can be sent to a std::stringstream. For example "foo: " << foo.
• args: A description of the function arguments as an expression like msg.
• condition: A boolean expression that can be passed to assert().

Typically, logging looks like this: @code{.cpp} bool checkStuff(Object o, bool flag) { LOG_FUNC("carl", o << ", " << flag); bool result = o.property(flag); LOGMSG_TRACE("carl", "Result: " << result); return result; } @endcode

Logging is enabled (or disabled) by the LOGGING macro in CMake.

Logging configuration

As of now, there is no frontend interface to configure logging. Hence, configuration is performed directly on the backend.

Logging backends

As of now, only two logging backends exist.

CArL logging

CArL provides a custom logging mechanism defined in carl::logging.

Fallback logging

If logging is enabled, but no real logging backend is selected, all logging of level WARN or above goes to std::cerr.