Provided by: libplack-perl_1.0047-1_all bug


       Plack::Middleware::Conditional - Conditional wrapper for Plack middleware


         use Plack::Builder;

         builder {
             enable_if { $_[0]->{REMOTE_ADDR} eq '' } 'StackTrace', force => 1;

         # or using the OO interface:
         $app = Plack::Middleware::Conditional->wrap(
             condition  => sub { $_[0]->{REMOTE_ADDR} eq '' },
             builder => sub { Plack::Middleware::StackTrace->wrap($_[0], force => 1) },


       Plack::Middleware::Conditional is a piece of meta-middleware, to run a specific middleware
       component under runtime conditions. The goal of this middleware is to avoid baking runtime
       configuration options in individual middleware components, and rather share them as
       another middleware component.


       Note that some of the middleware component names are just made up for the explanation and
       might not exist.

         # Minify JavaScript if the browser is Firefox
         enable_if { $_[0]->{HTTP_USER_AGENT} =~ /Firefox/ } 'JavaScriptMinifier';

         # Enable Stacktrace when being accessed from the local network
         enable_if { $_[0]->{REMOTE_ADDR} =~ /^10\.0\.1\.*/ } 'StackTrace';

         # Work with other conditional setter middleware:
         # Transcode Jpeg on the fly for mobile clients
         builder {
             enable 'MobileDetector';
             enable_if { $_[0]->{'plack.mobile_detected'} }
               'TranscodeJpeg', max_size => 30_000;

       Note that in the last example MobileDetector should come first because the conditional
       check runs in pre-run conditions, which is from outer to inner: that is, from the top to
       the bottom in the Builder DSL code.


       Tatsuhiko Miyagawa

       Steve Cook