public LogFunc default_handler
The default log handler set up by GLib; set_default_handler allows to install an alternate default log handler.
This is used if no log handler has been set for the particular log domain and log level combination. It outputs the message to stderr or
stdout and if the log level is fatal it calls breakpoint. It automatically prints a
new-line character after the message, so one does not need to be manually included in
The behavior of this log handler can be influenced by a number of environment variables:
- `G_MESSAGES_PREFIXED`: A :-separated list of log levels for which messages should be prefixed by the program name and PID of the application.
- `G_MESSAGES_DEBUG`: A space-separated list of log domains for which debug and informational messages are printed. By default these messages are not printed.
stderr is used for levels g_log_level_error, g_log_level_critical, g_log_level_warning and g_log_level_message. stdout is used for the rest, unless stderr was requested by writer_default_set_use_stderr.
This has no effect if structured logging is enabled; see Using Structured Logging.
the log domain of the message, or null for the default "" application domain
the level of the message
data passed from log which is unused