[log4perl-devel] Configuration file perl hooks

[Mike S. <msc...@ao...>]

Just checked in the configuration file perl hooks into CVS:

=head2 Perl Hooks in the Configuration File

If some of the values used in the Log4perl configuration file
need to be dynamically modified by the program, use Perl hooks:

    log4perl.appender.File.filename = \
        sub { return getLogfileName(); }

Each value starting with the string C<sub {...> is interpreted as Perl 
code to
be executed at the time the application parses the configuration
via C<Log::Log4perl::init()>. The return value of the subroutine
is used by Log::Log4perl as the configuration value.

The Perl code is executed in the C<main> package, functions in
other packages have to be called in fully-qualified notation.

Here's another example, utilizing an environment variable as a
username for a DBI appender:

    log4perl.appender.DB.username = \
        sub { $ENV{DB_USER_NAME } }

However, please note the difference between these code snippets and those
used for user-defined conversion specifiers as discussed in
L<Log::Log4perl::PatternLayout>: While the snippets above are run I<once>
when C<Log::Log4perl::init()> is called, the conversion specifier
snippets are executed I<each time> a message is rendered according to
the PatternLayout.

-- 
-- Mike

Mike Schilli
log...@pe...