dist_tools/

mg_log.pro

includes main-level program

MG_LOG is a procedural interface to the logging framework.

MG_LOG is a convenience routine so that the MGffLogger object does not need to be explicitly stored by the application using the logging. If more than one logger is required, then named loggers can be used using the NAME keyword.

The error levels are: critical (level 1), error (level 2), warning (level 3), informational (level 4), debug (level 5). Only log messages with a level less than or equal to the current logger level are actually recorded. So if a logger is set to level 3 (warnings), then log messages with levels 1 (critical), 2 (error), or 3 (warning) would be displayed, but log messages with levels 4 (informational) or 5 (debug) would be ignored.

Named subloggers can be created using the NAME keyword. These subloggers should be used for individual applications or functional areas of an application.

For example, the following starts the logging framework and creates a logger object with name "mg_example" returned via the LOGGER keyword:

  mg_log, name='mg_example', logger=logger

This logger would next be configured, i.e., set its level, specify a file for log messages to written to, set a format for log messages, etc. For example, to log critical errors, errors, and warnings to the file my_application.log, do:

  logger->setProperty, level=3, filename='my_application.log'

Later, messages can be sent to this logger by using the name used previously:

  mg_log, 'A problem occurred!', /warning, name='mg_example'

Further refinement can be done with a hierarchy of names. The following creates a new sublogger:

  mg_log, name='mg_example/gui', logger=gui_logger

This type of hierarchy is useful for applications with subsystems with independent level values. The effective log level for log messages sent to a sublogger is the most restrictive log level from all the parent loggers. For example, if the level of gui_logger was set to "Informational" with:

  gui_logger->setProperty, level=4

Then informational log messages would not be logged because the parent logger, "mg_example", has a level of 3, i.e., "Warning".

Examples

Try the main-level program at the end of this file for a longer example. To run it, do:

  IDL> .run mg_log

Routines

top mg_log

mg_log [, msg] [, arg1] [, arg2] [, arg3] [, arg4] [, arg5] [, arg6] [, name=string] [, /debug] [, /informational] [, /warning] [, /error] [, /critical] [, /last_error] [, logger=object] [, /quit] [, _extra=keywords]

Messages are logged via this routine. Also, the LOGGER keyword returns the logging object which is used to configure the logging.

Parameters

msg in optional type=string

message to log, if present; is interpreted as a format string when additional parameters are present

arg1 in optional type=string