3 Catalyst::Upgrading - Instructions for upgrading to the latest Catalyst
5 =head1 Upgrading to Catalyst 5.90
7 The major change is that L<Plack> now replaces most of the subclasses of
8 L<Catalyst::Engine>. If you are using one of the standard subclasses of
9 L<Catalyst::Engine> this should be a straightforward upgrade for you. It was
10 a design goal for this release to be as backwardly compatible as possible.
11 However since L<Plack> is different from L<Catalyst::Engine> it would be
12 possible that edge case differences would exist. Therefore we recommend care
13 be taken with this upgrade and that testing should be greater than would be
14 the case with a minor point update.
16 It is highly recommended that you become familar with the L<Plack> ecosystem
17 and documentation. Being able to take advantage of L<Plack> development and
18 middleware is a major bonus to this upgrade.
20 If you have created a custom subclass of L<Catalyst:Engine> you will need to
21 convert it to be a subclass of L<Plack::Handler>.
23 If you are using the L<Plack> engine, L<Catalyst::Engine::PSGI>, this new
24 release supercedes that code.
26 If you are using a subclass of L<Catalyst::Engine> that is aimed at nonstandard
27 or internal / testing uses, such as L<Catalyst::Engine::Embeddable> you should
28 still be able to continue using that engine.
30 Advice for specific subclasses of L<Catalyst::Engine> follows:
32 =head2 Upgrading the FastCGI Engine
34 No upgrade needed if your myapp_fastcgi.pl script is already upgraded
35 enough to use L<Catalyst::Script::FastCGI>.
37 =head2 Upgrading the mod_perl / Apache Engines
39 The engines that are build upon the various iterations of mod_perl,
40 L<Catalyst::Engine::Apache::MP13> and
41 L<Catalyst::Engine::Apache2::MP20> should be seemless upgrades and will
42 work using using L<Plack::Handler::Apache1> or L<Plack::Handler::Apache2>
45 L<Catalyst::Engine::Apache2::MP19>, is however no longer supported, as Plack
46 does not support mod_perl version 1.99??? FIXME - is this true?
48 =head2 Upgrading the HTTP Engine
50 The default development server that comes with the L<Catalyst> distribution
51 should continue to work as expected with no changes as long as your C<myapp_server>
52 script is upgraded to use L<Catalyst::Script::HTTP>.
54 =head2 Upgrading the CGI Engine
56 If you were using L<Catalyst::Engine::CGI> there is no upgrade needed if your
57 myapp_cgi.pl script is already upgraded enough to use L<Catalyst::Script::CGI>.
59 =head2 Upgrading the Preforking Engine
61 If you were using L<Catalyst::Engine::HTTP::Prefork> then L<Starman>
62 is automatically loaded.
64 XXX FIXME - note how to run Starman with different options.
66 =head2 Upgrading the PSGI Engine
68 If you were using L<Catalyst::Engine::PSGI> this new release supercedes this
69 engine in supporting L<Plack>. By default the Engine is now always L<Plack>.
70 As a result, you can stop depending on L<Catalyst::Engine::PSGI> in your
73 Applications that were using L<Catalyst::Engine::PSGI>
74 previously should entirely continue to work in this release with no changes.
76 However, if you have an C<app.psgi> script, then you no longer
77 need to specify the PSGI engine. Instead, the L<Catalyst> application class
78 now has a new method C<psgi_app> which returns a L<PSGI> compatible coderef
79 which you can wrap in middleware of your choice.
81 Catalyst will use the .psgi for your application if it is located in the C<home>
82 directory of the application
84 For example, if you were using L<Catalyst::Engine::PSGI> in the past, you will
85 have written (or generated) a C<script/myapp.psgi> file similar to this one:
90 MyCatalystApp->setup_engine('PSGI');
93 enable ... # enable your desired middleware
94 sub { MyCatalystApp->run(@_) };
103 enable ... #enable your desired middleware
104 MyCatalystApp->psgi_app;
107 And also rename C<< script/myapp.psgi >> to C<< myapp.psgi >>.
109 If you rename your .psgi file without these modifications, then any tests run via
110 L<Catalyst::Test> will not be compatible with the new release, and will result in
111 the development server starting, rather than the expected test running.
113 =head2 Engines which are known broken
115 The following engines B<DO NOT> work as of Catalyst version 5.90. The core
116 team is extremely happy to work with the developers and/or users of these
117 engines to help them port to the new Plack/Engine system, however applications
118 which are currently using these engines B<WILL NOT> run without modification
123 =item Catalyst::Engine::Wx
127 =head2 Engines with unknown status
129 The following engines have untested or unknown compatibility. Reports are
132 Catalyst::Engine::Embeddable - needs testing, should work?
133 Catalyst::Engine::XMPP2
134 Catalyst::Engine::SCGI
135 Catalyst::Engine::Mojo
136 Catalyst::Engine::Zeus - broken for ages
137 Catalyst::Engine::JobQueue::POE - broken for ages
138 Catalyst::Engine::Stomp - fixed
139 Catalyst::Engine::Server (Marked as Deprecated)
140 Catalyst::Engine::HTTP::POE (Marked as Deprecated)
142 =head2 Using middleware
144 XXX Should this be here or elsewhere?
146 =head2 Making an app.psgi file
148 =head2 Running with plackup?
150 =head1 Upgrading to Catalyst 5.80
152 Most applications and plugins should run unaltered on Catalyst 5.80.
154 However, a lot of refactoring work has taken place, and several changes have
155 been made which could cause incompatibilities. If your application or plugin
156 is using deprecated code, or relying on side effects, then you could have
157 issues upgrading to this release.
159 Most issues found with pre-existing components have been easy to
160 solve. This document provides a complete description of behavior changes
161 which may cause compatibility issues, and of new Catalyst warnings which
164 If you think you have found an upgrade-related issue which is not covered in
165 this document, please email the Catalyst list to discuss the problem.
167 =head1 Moose features
169 =head2 Application class roles
171 You can only apply method modifiers after the application's C<< ->setup >>
172 method has been called. This means that modifiers will not work with methods
173 which run during the call to C<< ->setup >>.
175 See L<Catalyst::Manual::ExtendingCatalyst> for more information about using
176 L<Moose> in your applications.
178 =head2 Controller actions in Moose roles
180 You can use L<MooseX::MethodAttributes::Role> if you want to declare actions
183 =head2 Using Moose in Components
185 The correct way to use Moose in a component in a both forward and backwards
188 package TestApp::Controller::Root;
190 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
192 See L<Components which inherit from Moose::Object before Catalyst::Component>.
194 =head1 Known backwards compatibility breakages
196 =head2 Applications in a single file
198 Applications must be in their own file, and loaded at compile time. This
199 issue generally only affects the tests of CPAN distributions. Your
200 application will fail if you try to define an application inline in a
201 block, and use plugins which supply a C< new > method, then use that
202 application latter in tests within the same file.
204 This is due to the fact that Catalyst is inlining a new method on your
205 application class allowing it to be compatible with Moose. The method
206 used to do this changed in 5.80004 to avoid the possibility of reporting
207 an 'Unknown Error' if your application failed to compile.
209 =head2 Issues with Class::C3
211 Catalyst 5.80 uses the L<Algorithm::C3> method dispatch order. This is
212 built into Perl 5.10, and comes via L<Class::C3> for Perl 5.8. This
213 replaces L<NEXT> with L<Class::C3::Adopt::NEXT>, forcing all components
214 to resolve methods using C3, rather than the unpredictable dispatch
217 This issue is characterised by your application failing to start due to an
218 error message about having a non-linear @ISA.
220 The Catalyst plugin most often causing this is
221 L<Catalyst::Plugin::Session::Store::FastMmap> - if you are using this
222 plugin and see issues, then please upgrade your plugins, as it has been
223 fixed. Note that Makefile.PL in the distribution will warn about known
224 incompatible components.
226 This issue can, however, be found in your own application - the only solution is
227 to go through each base class of the class the error was reported against, until
228 you identify the ones in conflict, and resolve them.
230 To be able to generate a linear @ISA, the list of superclasses for each
231 class must be resolvable using the C3 algorithm. Unfortunately, when
232 superclasses are being used as mixins (to add functionality used in your class),
233 and with multiple inheritence, it is easy to get this wrong.
235 Most common is the case of:
237 package Component1; # Note, this is the common case
238 use base qw/Class::Accessor::Fast Class::Data::Inheritable/;
240 package Component2; # Accidentally saying it this way causes a failure
241 use base qw/Class::Data::Inheritable Class::Accessor::Fast/;
244 use base qw/Component1 Component2/;
246 Any situation like this will cause your application to fail to start.
248 For additional documentation about this issue, and how to resolve it, see
249 L<Class::C3::Adopt::NEXT>.
251 =head2 Components which inherit from Moose::Object before Catalyst::Component
253 Moose components which say:
255 package TestApp::Controller::Example;
257 extends qw/Moose::Object Catalyst::Component/;
259 to use the constructor provided by Moose, while working (if you do some hacks
260 with the C< BUILDARGS > method), will not work with Catalyst 5.80 as
261 C<Catalyst::Component> inherits from C<Moose::Object>, and so C< @ISA > fails
264 The correct way to use Moose in a component in a both forward and backwards
267 package TestApp::Controller::Root;
269 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
271 Note that the C< extends > declaration needs to occur in a begin block for
272 L<attributes> to operate correctly.
274 This way you do not inherit directly from C<Moose::Object>
275 yourself. Having components which do not inherit their constructor from
276 C<Catalyst::Component> is B<unsupported>, and has never been recommended,
277 therefore you're on your own if you're using this technique. You'll need
278 to detect the version of Catalyst your application is running, and deal
279 with it appropriately.
281 You also don't get the L<Moose::Object> constructor, and therefore attribute
282 initialization will not work as normally expected. If you want to use Moose
283 attributes, then they need to be made lazy to correctly initialize.
285 Note that this only applies if your component needs to maintain component
286 backwards compatibility for Catalyst versions before 5.71001 - in 5.71001
287 attributes work as expected, and the BUILD method is called normally
288 (although BUILDARGS is not).
290 If you depend on Catalyst 5.8, then B<all> Moose features work as expected.
292 You will also see this issue if you do the following:
294 package TestApp::Controller::Example;
296 use base 'Catalyst::Controller';
298 as C< use base > appends to @ISA.
300 =head3 use Moose in MyApp
302 Similar to the above, this will also fail:
311 If you need to use Moose in your application class (e.g. for method modifiers
312 etc.) then the correct technique is:
320 __PACKAGE__->config( name => 'MyApp' );
321 __PACKAGE__->setup(qw/
325 =head2 Anonymous closures installed directly into the symbol table
327 If you have any code which installs anonymous subroutine references directly
328 into the symbol table, you may encounter breakages. The simplest solution is
329 to use L<Sub::Name> to name the subroutine. Example:
331 # Original code, likely to break:
332 my $full_method_name = join('::', $package_name, $method_name);
333 *$full_method_name = sub { ... };
336 use Sub::Name 'subname';
337 my $full_method_name = join('::',$package_name, $method_name);
338 *$full_method_name = subname $full_method_name, sub { ... };
340 Additionally, you can take advantage of Catalyst's use of L<Class::MOP> and
341 install the closure using the appropriate metaclass. Example:
344 my $metaclass = Moose::Meta::Class->initialize($package_name);
345 $metaclass->add_method($method_name => sub { ... });
347 =head2 Hooking into application setup
349 To execute code during application start-up, the following snippet in MyApp.pm
353 my ($class, @args) = @_;
354 $class->NEXT::setup(@args);
355 ... # things to do after the actual setup
358 With Catalyst 5.80 this won't work anymore, because Catalyst no longer
359 uses NEXT.pm for method resolution. The functionality was only ever
360 originally operational as L<NEXT> remembers what methods have already
361 been called, and will not call them again.
363 Using this now causes infinite recursion between MyApp::setup and
364 Catalyst::setup, due to other backwards compatibility issues related to how
365 plugin setup works. Moose method modifiers like C<< before|after|around setup
366 => sub { ... }; >> also will not operate correctly on the setup method.
368 The right way to do it is this:
370 after setup_finalize => sub {
371 ... # things to do after the actual setup
374 The setup_finalize hook was introduced as a way to avoid this issue.
376 =head2 Components with a new method which returns false
378 Previously, if you had a component which inherited from Catalyst::COMPONENT,
379 but overrode the new method to return false, then your class's configuration
380 would be blessed into a hash on your behalf, and this would be returned from
381 the COMPONENT method.
383 This behavior makes no sense, and so has been removed. Implementing your own
384 C< new > method in components is B<highly> discouraged. Instead, you should
385 inherit the new method from Catalyst::Component, and use Moose's BUILD
386 functionality and/or Moose attributes to perform any construction work
387 necessary for your class.
389 =head2 __PACKAGE__->mk_accessor('meta');
391 Won't work due to a limitation of L<Moose>. This is currently being fixed
394 =head2 Class::Data::Inheritable side effects
396 Previously, writing to a class data accessor would copy the accessor method
397 down into your package.
399 This behavior has been removed. While the class data is still stored
400 per-class, it is stored on the metaclass of the class defining the accessor.
402 Therefore anything relying on the side effect of the accessor being copied down
405 The following test demonstrates the problem:
409 use base qw/Class::Data::Inheritable/;
410 __PACKAGE__->mk_classdata('foo');
415 use base qw/BaseClass/;
418 BaseClass->foo('base class');
419 Child->foo('sub class');
422 isnt(BaseClass->can('foo'), Child->can('foo'));
424 =head2 Extending Catalyst::Request or other classes in an ad-hoc manner using mk_accessors
426 Previously, it was possible to add additional accessors to Catalyst::Request
427 (or other classes) by calling the mk_accessors class method.
429 This is no longer supported - users should make a subclass of the class whose
430 behavior they would like to change, rather than globally polluting the
433 =head2 Confused multiple inheritance with Catalyst::Component::COMPONENT
435 Previously, Catalyst's COMPONENT method would delegate to the method on
436 the right hand side, which could then delegate back again with
437 NEXT. This is poor practice, and in addition, makes no sense with C3
438 method dispatch order, and is therefore no longer supported.
440 If a COMPONENT method is detected in the inheritance hierarchy to the right
441 hand side of Catalyst::Component::COMPONENT, then the following warning
442 message will be emitted:
444 There is a COMPONENT method resolving after Catalyst::Component
447 The correct fix is to re-arrange your class's inheritance hierarchy so that the
448 COMPONENT method you would like to inherit is the first (left-hand most)
449 COMPONENT method in your @ISA.
453 =head2 Actions in your application class
455 Having actions in your application class will now emit a warning at application
456 startup as this is deprecated. It is highly recommended that these actions are moved
457 into a MyApp::Controller::Root (as demonstrated by the scaffold application
458 generated by catalyst.pl).
460 This warning, also affects tests. You should move actions in your test,
461 creating a myTest::Controller::Root, like the following example:
463 package MyTest::Controller::Root;
468 use parent 'Catalyst::Controller';
470 __PACKAGE__->config(namespace => '');
473 my ( $self, $c ) = @_;
479 =head2 ::[MVC]:: naming scheme
481 Having packages called MyApp::[MVC]::XX is deprecated and can no longer be generated
484 This is still supported, but it is recommended that you rename your application
485 components to Model/View/Controller.
487 A warning will be issued at application startup if the ::[MVC]:: naming scheme is
490 =head2 Catalyst::Base
492 Any code using L<Catalyst::Base> will now emit a warning; this
493 module will be removed in a future release.
495 =head2 Methods in Catalyst::Dispatcher
497 The following methods in Catalyst::Dispatcher are implementation
498 details, which may change in the 5.8X release series, and therefore their use
499 is highly deprecated.
507 =item registered_dispatch_types
509 =item method_action_class
517 The first time one of these methods is called, a warning will be emitted:
519 Class $class is calling the deprecated method Catalyst::Dispatcher::$public_method_name,
520 this will be removed in Catalyst 5.9X
522 You should B<NEVER> be calling any of these methods from application code.
524 Plugin authors and maintainers whose plugins currently call these methods
525 should change to using the public API, or, if you do not feel the public API
526 adequately supports your use case, please email the development list to
527 discuss what API features you need so that you can be appropriately supported.
529 =head2 Class files with names that don't correspond to the packages they define
531 In this version of Catalyst, if a component is loaded from disk, but no
532 symbols are defined in that component's name space after it is loaded, this
533 warning will be issued:
535 require $class was successful but the package is not defined.
537 This is to protect against confusing bugs caused by mistyping package names,
538 and will become a fatal error in a future version.
540 Please note that 'inner packages' (via L<Devel::InnerPackage>) are still fully
541 supported; this warning is only issued when component file naming does not map
542 to B<any> of the packages defined within that component.
544 =head2 $c->plugin method
546 Calling the plugin method is deprecated, and calling it at run time is B<highly
549 Instead you are recommended to use L<Catalyst::Model::Adaptor> or similar to
550 compose the functionality you need outside of the main application name space.
552 Calling the plugin method will not be supported past Catalyst 5.81.