Re: [log4perl-devel] Buffer problem

[Kevin M. G. <cp...@go...>]

I thought this would be a quick, easy answer, but there's actually a
couple things going on:

 1) since you're using qq() to enclose the string containing your
config, all the $'s and \'s are being interpolated by perl when the
script loads.  Use q() instead--it's like single quotes around a string,
so there is no interpolation.

2) It looks like the docs for trigger are just a little bit wrong.  To
get the desired behavior, you currently have to wrap your sub in another
sub, like this:

	log4perl.appender.Buffer.trigger = sub { sub{return 1} }

I'll propose a fix to Mike in a separate note to the list.

3) The comparison inside the trigger also won't work the way the docs
are written. You'll need something like this, which is inherently
inefficient and uses some internal functions, but it's a quick answer:

 log4perl.appender.Buffer.trigger = sub {   \
   my($self, $params) = @_;             \
   return                               \
    Log::Log4perl::Level::to_priority($params->{log4p_level}) \
			>=               \
    Log::Log4perl::Level::to_priority('ERROR')  }



Robert Jacobson wrote:
> I'm trying to use the "trigger" function of Buffer, but I can't seem 
> to get it to work.  I just took the examples from the perldoc and 
> stuck them together:
> 
>      use Log::Log4perl qw(:easy);
> 
>      my $conf = qq(
>      log4perl.category                  = DEBUG, Buffer
> 
>          # Regular Screen Appender
>      log4perl.appender.Screen           = Log::Log4perl::Appender::Screen
>      log4perl.appender.Screen.stdout    = 1
>      log4perl.appender.Screen.layout    = PatternLayout
>      log4perl.appender.Screen.layout.ConversionPattern = %d %p %c %m %n
> 
>          # Buffering appender, using the appender above as outlet
>              log4perl.appender.Buffer               = 
> Log::Log4perl::Appender::Buffer
>              log4perl.appender.Buffer.appender      = Screen
>              log4perl.appender.Buffer.trigger = sub {   \
>          my($self, $params) = @_;               \
>          return $params->{log4p_level} >=       \
>                 $Log::Log4perl::Level::ERROR; }
>              );
> 
>      Log::Log4perl->init(\$conf);
> 
>      DEBUG("This message gets buffered.");
>      INFO("This message gets buffered also.");
> 
>      # Time passes. Nothing happens. But then ...
> 
>      print "It's GO time!!!\n";
> 
>      ERROR("This message triggers a buffer flush.");
> 
> 
> But when I run the above I get:
> 
> Can't evaluate 'sub {' (Missing right curly or square bracket at 
> (eval 9) line 2, at end of line
> syntax error at (eval 9) line 2, at EOF
> ) at /opt/ActivePerl-5.8/lib/site_perl/5.8.7/Log/Log4perl/Config.pm line 741.
> 
> 
> Even a simple "return 1" doesn't work, i.e.:
> 	log4perl.appender.Buffer.trigger = sub {return 1;}
> 
> Am I missing something simple? (again? :)  )
> 
> 
> --
> Rob
> 
> 
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