NAME

Plack::Builder - OO and DSL to enable Plack Middlewares

SYNOPSIS

# in .psgi
use Plack::Builder;

my $app = sub { ... };

builder {
    enable "Plack::Middleware::Foo";
    enable "Plack::Middleware::Bar", opt => "val";
    enable "Plack::Middleware::Baz";
    $app;
};

# use URLMap

builder {
    mount "/foo" => builder {
        enable "Plack::Middleware::Foo";
        $app;
    };

    mount "/bar" => $app2;
    mount "http://example.com/" => builder { $app3 };
};

DESCRIPTION

Plack::Builder gives you a quick domain specific language (DSL) to wrap your application with Plack::Middleware subclasses. The middleware you're trying to use should use Plack::Middleware as a base class to use this DSL, inspired by Rack::Builder.

Whenever you call add on any middleware, the middleware app is pushed to the stack inside the builder, and then reversed when it actually creates a wrapped application handler, so:

builder {
    enable "Plack::Middleware::Foo";
    enable "Plack::Middleware::Bar", opt => "val";
    $app;
};

is syntactically equal to:

$app = Plack::Middleware::Bar->wrap($app, opt => "val");
$app = Plack::Middleware::Foo->wrap($app);

In other words, you're supposed to add middleware from outer to inner.

URLMap support

Plack::Builder has a native support for Plack::App::URLMap with mount method.

use Plack::Builder;
my $app = builder {
    mount "/foo" => $app1;
    mount "/bar" => builder {
        enable "Plack::Middleware::Foo";
        $app2;
    };
};

See Plack::App::URLMap's map method to see what they mean. With builder you can't use map as a DSL, for the obvious reason :)

SEE ALSO

Plack::Middleware Plack::App::URLMap