[log4perl-devel] Suggested update to the POD

[Steven L. <le...@wr...>]

The wrapper-level variable probably should be
localized by any class that wraps L4p: there's
no guarantee that no-one will call an un-wrapped
method in L4p and botch the sequcnes.

=head1 Using Log::Log4perl from wrapper classes

If you don't use C<Log::Log4perl> as described above,
but from a wrapper class (like your own Logging class which in turn uses
C<Log::Log4perl>),
the pattern layout will generate wrong data for %F, %C, %L and the like.
Reason for this is that C<Log::Log4perl>'s loggers assume a static
caller depth to the application that's using them. If you're using
one (or more) wrapper classes, C<Log::Log4perl> will indicate where
your logger classes called the loggers, not where your application
called your wrapper, which is probably what you want in this case.

But don't despair, there's a solution: Just increase the value
of C<$Log::Log4perl::caller_depth> (defaults to 0) by one for every
wrapper that's in between your application and C<Log::Log4perl>,
then C<Log::Log4perl> will compensate for the difference.

Using a local variable avoids problems with anyone who
uses Log4perl directly; using ||= allows people to wrap
YOUR wrappers without accidentally resetting the value
too low.

    sub debug
    {
        local $Log::Log4perl::caller_depth  ||= 1;

        ...
    }

-- 
Steven Lembark                                          +1 888 359 3508
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