Add “object” type of argument for Plack::Runner

lib/Plack/Runner.pm

@@ -160,6 +160,10 @@ sub locate_app {
         return sub { $psgi };
     }
 
+    if (Scalar::Util::blessed($psgi) and $psgi->can('to_app')){
+        return sub { $psgi->to_app };
+    }
+
     if ($self->{eval}) {
         $self->loader->watch("lib");
         return build {
@@ -295,6 +299,20 @@ Plack::Runner - plackup core
   $runner->parse_options(@ARGV);
   $runner->run($app);
 
+  # use app builder instead of app
+  use Plack::Runner;
+  my $app_builder => sub {
+          # do some thing here will run every time server loaded
+
+          return sub  {
+                # the real app code here
+          }
+  };
+
+  my $runner = Plack::Runner->new;
+  $runner->parse_options(@ARGV);
+  $runner->run(\$app_builder); # use code ref ref
+
 =head1 DESCRIPTION
 
 Plack::Runner is the core of L<plackup> runner script. You can create

t/Plack-Runner/app_builder.t

@@ -0,0 +1,83 @@
+
+use Test::More;
+use Plack::Runner;
+use File::Path     (qw/make_path remove_tree/);
+use Test::Requires (qw/LWP::UserAgent Test::MockObject/);
+
+make_path "tmp/m";
+
+my $app = Test::MockObject->new();
+$app->mock(
+    to_app => sub {
+        eval {
+            open my $fh, ">>", "tmp/counter";
+            print $fh "1";
+            close $fh;
+        };
+        return sub {
+            return [ 200, [], ["Hello"] ];
+          }
+    }
+);
+
+my $runner = Plack::Runner->new;
+
+sub counter_ok {
+    my ( $len, $msg ) = @_;
+    my $content = "";
+    eval {
+        open my $fh, "<", "tmp/counter";
+        $content = <$fh>;
+
+    };
+    is $content , "1" x $len, $msg;
+}
+
+$runner->parse_options( -R => 'tmp/m', '-r', -p => 5000 );
+
+my $pid = fork;
+
+if ($pid) {
+    my $timeout = 5;
+    until ( -f "tmp/counter" ) {
+        sleep 1;
+        last if $timeout-- == 0;
+    }
+    if ( $timeout < 0 ) {
+        is 1 < 0, "plack up server failed";
+        kill 'TERM' => $pid;
+    }
+    else {
+        my $ua  = LWP::UserAgent->new;
+        my $res = $ua->get('http://127.0.0.1:5000/');
+        ok $res->is_success;
+        is $res->code,    200;
+        is $res->content, 'Hello';
+
+        counter_ok 1, "app builder not run";
+
+        make_path "tmp/m/a";
+        sleep 5;
+
+        counter_ok 2, "app builder run";
+        $res = $ua->get('http://127.0.0.1:5000/');
+        ok $res->is_success;
+        is $res->code,    200;
+        is $res->content, 'Hello';
+
+        remove_tree "tmp/m/a";
+        sleep 5;
+
+        counter_ok 3, "app builder run again";
+
+        kill 'TERM' => $pid;
+    }
+}
+else {
+    $runner->run($app);
+    exit 0;
+}
+
+remove_tree "tmp";
+done_testing;
+