Hello,

Recently I discovered Log::Log4perl. This is such a great piece of work that after a week of using it I'm almost wondering how could I live without it before. But there are things about it I have not been able to figure out by studying the documentation.

Here is my problem:

I want to indent log messages by stack depth (for tracing program execution), and although Log::Log4perl itself does not directly support this, I have managed (with help from the Internet, including Perl Monks) to have it my way — almost. I added the following lines to log4perl.conf:

log4perl.PatternLayout.cspec.S = sub { return '    ' x level_for_l4p()
+; }
log4perl.appender.std.layout.ConversionPattern  = %-27F %3L %S%m%n
[download]

and defined level_for_l4p() in my main program:

my $zerolevel = 8;
sub level_for_l4p {
    my $level = 0;
    1 while caller( $level++ );
    return ( $level - $zerolevel );
}
Log::Log4perl::init( 'log4perl.conf' );
[download]

(Appropriate numbers for $zerolevel and %F are easily found by trial and error.)

Logs produced by this setup look basically like this:

/My/Project/One/File.pm      12    sub0: calling sub1
/My/Project/Another/File.pm  96        sub1: entering
/My/Project/Another/File.pm 105        sub1: calling sub2
/My/Project/Elsewhere.pm     72           sub2: entering
/My/Project/Elsewhere.pm     84           sub2: leaving
/My/Project/Another/File.pm 108        sub1: continuing after sub2
/My/Project/Another/File.pm 115        sub1: leaving
/My/Project/One/File.pm      16    sub0: continuing after sub1
# etc.
[download]

In principle, this is exactly what I want, but I don't like the appearance of the output: IMHO it fails miserably to please the eye.

I'd much prefer being able to have the log output look like this:

/My/Project/One/File.pm:12:         sub0: calling sub1
/My/Project/Another/File.pm:96:         sub1: entering
/My/Project/Another/File.pm:105:        sub1: calling sub2
/My/Project/Elsewhere.pm:72:                sub2: entering
/My/Project/Elsewhere.pm:84:                sub2: leaving
/My/Project/Another/File.pm:108:        sub1: continuing after sub2
/My/Project/Another/File.pm:115:        sub1: leaving
/My/Project/One/File.pm:16:         sub0: continuing after sub1
[download]

which would also have the additional benefit of working right out of the box with Emacs' default compilation-error-regexp-alist. To achieve this, it should be possible to say something like %-32{%F:%L:}, i.e. to tell Log::Log4perl to set the total length for %F:%L: as a unit. But I have not been able to find a way to express my intention.

Is it possible to do what I want? In case I'm missing something obvious, can anybody point me to an existing and/or simple solution?

I am using Log::Log4perl 1.47 and Perl 5.20.0.

Cheers,
T.

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