2 More Discussions You Might Find Interesting
1. Programming
If anyone uses this can you help please;
I want to use a for loop to update several Objects without having to write them all into the script, e.g.,
If I have CheckBox1, CheckBox2, CheckBox3 etc I want loop round something like
for (int i=1;i<10;i++)
CheckBox(i)->State = 1;
Where... (1 Reply)
Discussion started by: gefa
1 Replies
2. Programming
Hello everybody there,
I wanted to know, if any builder(RAD) existed for programming in gcc(g++)/c++ in Linux. I am using scientific Linux. I need it urgently if it exists.
--rohit (1 Reply)
Discussion started by: RohitThakkar
1 Replies
LEARN ABOUT DEBIAN
plack::builder
Plack::Builder(3pm) User Contributed Perl Documentation Plack::Builder(3pm)
NAME
Plack::Builder - OO and DSL to enable Plack Middlewares
SYNOPSIS
# in .psgi
use Plack::Builder;
my $app = sub { ... };
builder {
enable "Deflater";
enable "Session", store => "File";
enable "Debug", panels => [ qw(DBITrace Memory Timer) ];
enable "+My::Plack::Middleware";
$app;
};
# use URLMap
builder {
mount "/foo" => builder {
enable "Foo";
$app;
};
mount "/bar" => $app2;
mount "http://example.com/" => builder { $app3 };
};
# using OO interface
my $builder = Plack::Builder->new();
$builder->add_middleware('Foo', opt => 1);
$app = $builder->mount('/app' => $app);
$app = $builder->to_app($app);
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 "enable" 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. "Plack::Middleware::" is added as a prefix by default. So:
builder {
enable "Foo";
enable "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 "enable" middleware from outer to inner.
INLINE MIDDLEWARE
Plack::Builder allows you to code middleware inline using a nested code reference.
If the first argument to "enable" is a code reference, it will be passed an $app and is supposed to return another code reference which is
PSGI application that consumes $env in runtime. So:
builder {
enable sub {
my $app = shift;
sub {
my $env = shift;
# do preprocessing
my $res = $app->($env);
# do postprocessing
return $res;
};
};
$app;
};
is equal to:
my $mw = sub {
my $app = shift;
sub { my $env = shift; $app->($env) };
};
$app = $mw->($app);
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 "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 :)
NOTE: Once you use "mount" in your builder code, you have to use "mount" for all the paths, including the root path ("/"). You can't have
the default app in the last line of "builder" like:
my $app = sub {
my $env = shift;
...
};
builder {
mount "/foo" => sub { ... };
$app; # THIS DOESN'T WORK
};
You'll get warnings saying that your mount configuration will be ignored. Instead you should use "mount "/" => ..." in the last line to set
the default fallback app.
builder {
mount "/foo" => sub { ... };
mount "/" => $app;
}
Note that the "builder" DSL returns a whole new PSGI application, which means
o "builder { ... }" should normally the last statement of a ".psgi" file, because the return value of "builder" is the application that
actually is executed.
o You can nest your "builder" block, mixed with "mount" (see URLMap support above):
builder {
mount "/foo" => builder {
mount "/bar" => $app;
}
}
will locate the $app under "/foo/bar" since the inner "builder" block puts it under "/bar" and it results a new PSGI application which
is located under "/foo" because of the outer "builder" block.
CONDITIONAL MIDDLEWARE SUPPORT
You can use "enable_if" to conditionally enable middleware based on the runtime environment. See Plack::Middleware::Conditional for
details.
SEE ALSO
Plack::Middleware Plack::App::URLMap Plack::Middleware::Conditional
perl v5.14.2 2012-05-17 Plack::Builder(3pm)