5.2 Log Messages

OOMMF defines a Tcl-based log class, Oc_Log, which is available at the Tcl script level in all OOMMF applications. Messages are specified using the syntax

  Oc_Log Log message_content message_level

where message_content is an arbitrary string and message_level is one of the predefined log levels: debug, status, info, debug, warning, error, or panic. Messages at level warning or higher are delivered by default using the standard log handler, which is a pop-up window for Tk-based applications or stderr for console applications.

Lower-level messages may be voluminous and are typically only useful for debugging, so are not reported (i.e., swallowed) in OOMMF builds configured for release. For development work, however, it can be useful to record to a file all levels of log messages. This can be done by including a code block similar to the following in the application Tcl initialization code section, following the package require Oc command:

Oc_FileLogger SetFile fubar.log
Oc_FileLogger StderrEcho 0
Oc_Log SetLogHandler [list Oc_FileLogger Log] panic
Oc_Log SetLogHandler [list Oc_FileLogger Log] error
Oc_Log SetLogHandler [list Oc_FileLogger Log] warning
Oc_Log SetLogHandler [list Oc_FileLogger Log] info
Oc_Log SetLogHandler [list Oc_FileLogger Log] status
Oc_Log SetLogHandler [list Oc_FileLogger Log] debug

Here fubar.log is an arbitrary name for the log file. Each run will append to any preceding messages, so you may want to include a start message such as

Oc_Log Log "*** Application fubar start ***" status

following the SetLogHandler commands to easily distinguish between runs.

The Oc_FileLogger StderrEcho 0 command disables duplication of the log messages to stderr. Replace 0 with 1 if you want log messages written to both the log file and stderr.

Concerning stderr output on Windows, Tk enabled OOMMF applications (e.g., mmLaunch and applications launched by mmLaunch) are by default launched using WINDOWS subsystem shell executables rather than ones built with the CONSOLE subsystem. Writes to stdout and stderr from such applications do not appear in the command prompt console window. To change this, launch the application directly using the console variant of the shell executable, e.g.,

> oommf mmlaunch +command
app/omfsh/windows-x86_64/omfsh.exe app/mmlaunch/mmlaunch.tcl &
> dir /w app\omfsh\windows-x86_64
Directory of oommf\app\omfsh\windows-x86_64
[.]       [..]      appindex.tcl   filtersh.exe   omfsh.exe   omfsh.obj
> app\omfsh\windows-x86_64\filtersh app\mmlaunch\mmlaunch.tcl

In this example the OOMMF application mmlaunch uses the omfsh (WINDOWS subsystem) shell by default, so we replace this with filtersh. The corresponding command to run mmDisp would be

> app\mmdisp\windows-x86_64\condispsh app\mmdisp\scripts\mmdisp.tcl

where condispsh stands in for mmdispsh.