[log4perl-devel] log4perl enhancement request ?

[Pete S. <si...@uc...>]

I'd like log4perl to indent messages to show caller depth in the call
stack.  A sample of this style is

  main: starting
    function1: called with arg1, arg2
    function1: returning value1
    function2: called
      function3: called
        function4: called with arg4
        function4: returning
      function3: returning
    function2: returning
  main: ending

For years, I've been doing this by passing around a scalar named
$CallDepth, and incrementing/decrementing it at function entry/exit.  I
pass around a second scalar named $DbgLevel that works sorta like the
levels in log4perl, but with more levels.  In the above sample, setting
it to 1 shows only the "main" lines, and 2 shows only "main" and
"function1" and "function2", etc.  I set the DbgLevel with a
command-line option, so I can produce logs with shallow or deep
hierarchies.  This scheme has been extremely useful for me, though a bit
cumbersome.  It even handles recursion nicely.

It seems like "Custom Cspecs" in PatternLayouts is the way to do this in
log4perl.  It's described at
http://log4perl.sourceforge.net/releases/Log-Log4perl/docs/html/Log/Log4perl/Layout/PatternLayout.html#9af52
The $caller_level variable is especially intriguing, as it's *almost*
what I need.  Instead of being "how many levels back up the call stack
you have to go to find the caller", which isn't very useful, I want it
to be "how many levels back up the call stack you have to go to find the
main program".  Perhaps "main program" could be defined by a new
function to mark the "zero" depth of the stack.

I confess to being a little lost as to how to do this, but I think it's
possible.  Am I crazy?

-- Pete