Perl Dancer for Python programmers

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This is a talk given at PyWeb IL Oct 4th.

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Perl Dancer for Python programmers

  1. 1. Dancer (the Effortless Perl Web Framework)
  2. 2. About me ● Sawyer X ● Sysadmin / Perl Ninja ● Israel.pm / Haifa.pm / TelAviv.pm / Rehovot.pm ● I do system, networking, web, applications, etc. ● http://blogs.perl.org/users/sawyer_x/ ● http://search.cpan.org/~xsawyerx/
  3. 3. Perl web recap 1995 CGI
  4. 4. Perl web recap 2010 Many frameworks (including micro-frameworks like Dancer)
  5. 5. The big web religions, illustrated
  6. 6. Ruby – the fanboys
  7. 7. Python – the sticklers
  8. 8. PHP – the nonsensical
  9. 9. Perl – the nutcases
  10. 10. Nutcases? ● Yes, we are insane (but not LISP-insane) ● Insanity is a whole lot of fun! ● Insanity gives us flexibility ● Flexibility gives us cool stuff ● Like Moose and meta-programming ● Like DBIx::Class ● Like Dancer
  11. 11. Flask (Pythonese) from flask import Flask app = Flask(__name__) @app.route("/", methods=['GET']) def hello():     return "Hello World!" if __name__ == "__main__":     app.run()
  12. 12. Dancer (Perlesque) use Dancer; get “/hi” => sub {     “Hello, World!” }; dance;
  13. 13. In comparison from flask import Flask use Dancer; app = Flask(__name__) @app.route("/", methods=['GET']) get “/” => sub { def hello():   “Hello, World!”     return "Hello World!" }; if __name__ == "__main__":     app.run() dance;
  14. 14. Dancer treats ● Both read and write, easily! ● Route-based (started as a port of Sinatra) ● PSGI/Plack compliant (PSGI is our WSGI) ● Minimum dependencies ● Any app is also a web server ● CPAN-friendly (<3 CPAN)
  15. 15. Recipe for Dancing ● Take an HTTP method ● Add a path to that ● Mix with a subroutine ● And sprinkle plugins and keywords on top
  16. 16. Dancer route structure get     '/path' => sub { … }; post    '/path' => sub { … }; put     '/path' => sub { … }; del     '/path' => sub { … }; options '/path' => sub { … }; any     '/path' => sub { … };
  17. 17. Dancer ● Paths can contain variables get '/hello/:entity/' ● Paths can be Regular Expressions get qr{/ (w+) / d{2,3} (.+)? }x
  18. 18. Dancer login example post '/login' => sub {     # Validate the username and password     if ( params­>{user} eq 'bob' &&          params­>{pass} eq 'LetMeIn' ) {         session user => params­>{user};         redirect params­>{path} || '/';     } else {         redirect '/login?failed=1';     }  };
  19. 19. Templating get '/' => sub {     template index => {         greeting => 'welcome'     } };
  20. 20. More nifty stuff ● headers 'My­X­Header' => 'Value' ● send_file('report.tar.gz') ● set_cookie name    => 'value',            expires => ( time + 3600 ),            domain  => 'foo.com' ● status 'not_found' ● to_json, to_yaml, to_xml ● my $file        = upload('file_input') ● my $all_uploads = request­>uploads
  21. 21. Dancer as Perl philosophy ● Dancer is succinct, efficient and easy to work with ● Dancer is daring (Do you have route caching in Django?) (Websockets in near future!) ● Dancer has a lot of plugins: (engines for sessions, logging, templates) ● Serializers (JSON, YAML, XML) ● Route filters (before, after, before_template)
  22. 22. Oh yeah, route caching...
  23. 23. Dancer::Plugin::REST get '/user/:id.:format' => sub {     UserRS­>find( params­>{id} ); }; # curl http://mywebservice/user/42.json { "id": 42, "name": "John Foo",              "email": "john.foo@hopkins.com" } # curl http://mywebservice/user/42.yml ­­ id: 42 name: "John Foo" email: "john.foo@hopkins.com"
  24. 24. Dancer::Plugin::SiteMap use Dancer::Plugin::SiteMap; ● You get: /sitemap and /sitemap.xml ● “Yup, it's that simple.”
  25. 25. Dancer::Plugin::Email post '/contact' => sub {     email {         to      => 'a@b.com',         subject => 'Test',         message => $msg,         attach  => [ path => 'name' ],     } };
  26. 26. Dancer::Plugin::Authorize post '/login' => sub {     my $user = params­>{'user'};     my $pass = params­>{'pass'};     if ( auth( $user, $pass ) ) {         if ( auth_asa('guest')  ) {...}         if ( auth_can('create') ) {...}     } };
  27. 27. Dancer::Plugin::Ajax ajax '/check_for_update' => sub {     # some ajax code }; ● Pass if X-Request-With not “XMLHttpRequest” ● Disable the layout ● The action built is a POST request
  28. 28. Dancer::Plugin::DBIC ● DBIC (DBIx::Class) – a sophisticated ORM ● Configure the connection in the config file ● Make the ResultSets available in routes
  29. 29. Dancer::Plugin::Database ● Database(s) connection in Dancer get '/widget/view/:id' => sub {    my $sth = database­>prepare(         'select * from widgets where id = ?'    );    $sth­>execute( params­>{id} );    template display_widget => {        widget => $sth­>fetchrow_hashref,    }; };
  30. 30. In culmination Dancer is beautiful and fun The way programming should be PerlDancer.org search.cpan.org/perldoc?Dancer

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