3 Catalyst::Upgrading - Instructions for upgrading to the latest Catalyst
5 =head2 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
36 =head2 Upgrading the mod_perl / Apache Engines
38 The three engines that are build upon the various iterations of mod_perl,
39 L<Catalyst::Engine::Apache2::MP19>, L<Catalyst::Engine::Apache::MP13> and
40 L<Catalyst::Engine::Apache2::MP20> should be seemless upgrades and will
41 work using using L<Plack::Handler::Apache1> or L<Plack::Handler::Apache2>
44 =head2 Upgrading the HTTP Engine
46 If you were using L<Catalyst::Engine::HTTP> (the default development server
47 that comes with the L<Catalyst> distribution) you should now use...
51 =head2 Upgrading the CGI Engine
53 If you were using L<Catalyst::Engine::CGI> you should now use...
57 =head2 Upgrading the Preforking Engine
59 If you were using L<Catalyst::Engine::HTTP::Prefork> you should now use...
63 =head2 Upgrading the Restarter Engines
65 If you were using L<Catalyst::Engine::HTTP::Restarter> or
66 L<Catalyst::Engine::HTTP::Restarter::Watcher> these are now longer part of the
67 L<Catalyst> distribution. You should now use...
71 =head2 Upgrading the PSGI Engine
73 If you were using L<Catalyst::Engine::PSGI> this new release supercedes this
74 engine in supporting L<Plack>. You should now do...
78 =head2 Engines with unknown status
80 The following engines have untested or unknown compatibility. Reports are
83 Catalyst::Engine::Embeddable
84 Catalyst::Engine::XMPP2
85 Catalyst::Engine::SCGI
86 Catalyst::Engine::Mojo
87 Catalyst::Engine::Zeus
88 Catalyst::Engine::JobQueue::POE
90 Catalyst::Engine::Stomp
91 Catalyst::Engine::Server (Marked as Deprecated)
92 Catalyst::Engine::HTTP::POE (Marked as Deprecated)
94 =head2 Engines known to not be compatible.
96 If you are using one of the following L<Catalyst::Engine> subclasses, your
97 application may require significant work after upgrading. We recommend you
98 test heavily and sandbox your upgrade.
102 =head1 Upgrading to Catalyst 5.80
104 Most applications and plugins should run unaltered on Catalyst 5.80.
106 However, a lot of refactoring work has taken place, and several changes have
107 been made which could cause incompatibilities. If your application or plugin
108 is using deprecated code, or relying on side effects, then you could have
109 issues upgrading to this release.
111 Most issues found with pre-existing components have been easy to
112 solve. This document provides a complete description of behavior changes
113 which may cause compatibility issues, and of new Catalyst warnings which
116 If you think you have found an upgrade-related issue which is not covered in
117 this document, please email the Catalyst list to discuss the problem.
119 =head1 Moose features
121 =head2 Application class roles
123 You can only apply method modifiers after the application's C<< ->setup >>
124 method has been called. This means that modifiers will not work with methods
125 which run during the call to C<< ->setup >>.
127 See L<Catalyst::Manual::ExtendingCatalyst> for more information about using
128 L<Moose> in your applications.
130 =head2 Controller actions in Moose roles
132 You can use L<MooseX::MethodAttributes::Role> if you want to declare actions
135 =head2 Using Moose in Components
137 The correct way to use Moose in a component in a both forward and backwards
140 package TestApp::Controller::Root;
142 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
144 See L<Components which inherit from Moose::Object before Catalyst::Component>.
146 =head1 Known backwards compatibility breakages
148 =head2 Applications in a single file
150 Applications must be in their own file, and loaded at compile time. This
151 issue generally only affects the tests of CPAN distributions. Your
152 application will fail if you try to define an application inline in a
153 block, and use plugins which supply a C< new > method, then use that
154 application latter in tests within the same file.
156 This is due to the fact that Catalyst is inlining a new method on your
157 application class allowing it to be compatible with Moose. The method
158 used to do this changed in 5.80004 to avoid the possibility of reporting
159 an 'Unknown Error' if your application failed to compile.
161 =head2 Issues with Class::C3
163 Catalyst 5.80 uses the L<Algorithm::C3> method dispatch order. This is
164 built into Perl 5.10, and comes via L<Class::C3> for Perl 5.8. This
165 replaces L<NEXT> with L<Class::C3::Adopt::NEXT>, forcing all components
166 to resolve methods using C3, rather than the unpredictable dispatch
169 This issue is characterised by your application failing to start due to an
170 error message about having a non-linear @ISA.
172 The Catalyst plugin most often causing this is
173 L<Catalyst::Plugin::Session::Store::FastMmap> - if you are using this
174 plugin and see issues, then please upgrade your plugins, as it has been
175 fixed. Note that Makefile.PL in the distribution will warn about known
176 incompatible components.
178 This issue can, however, be found in your own application - the only solution is
179 to go through each base class of the class the error was reported against, until
180 you identify the ones in conflict, and resolve them.
182 To be able to generate a linear @ISA, the list of superclasses for each
183 class must be resolvable using the C3 algorithm. Unfortunately, when
184 superclasses are being used as mixins (to add functionality used in your class),
185 and with multiple inheritence, it is easy to get this wrong.
187 Most common is the case of:
189 package Component1; # Note, this is the common case
190 use base qw/Class::Accessor::Fast Class::Data::Inheritable/;
192 package Component2; # Accidentally saying it this way causes a failure
193 use base qw/Class::Data::Inheritable Class::Accessor::Fast/;
196 use base qw/Component1 Component2/;
198 Any situation like this will cause your application to fail to start.
200 For additional documentation about this issue, and how to resolve it, see
201 L<Class::C3::Adopt::NEXT>.
203 =head2 Components which inherit from Moose::Object before Catalyst::Component
205 Moose components which say:
207 package TestApp::Controller::Example;
209 extends qw/Moose::Object Catalyst::Component/;
211 to use the constructor provided by Moose, while working (if you do some hacks
212 with the C< BUILDARGS > method), will not work with Catalyst 5.80 as
213 C<Catalyst::Component> inherits from C<Moose::Object>, and so C< @ISA > fails
216 The correct way to use Moose in a component in a both forward and backwards
219 package TestApp::Controller::Root;
221 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
223 Note that the C< extends > declaration needs to occur in a begin block for
224 L<attributes> to operate correctly.
226 This way you do not inherit directly from C<Moose::Object>
227 yourself. Having components which do not inherit their constructor from
228 C<Catalyst::Component> is B<unsupported>, and has never been recommended,
229 therefore you're on your own if you're using this technique. You'll need
230 to detect the version of Catalyst your application is running, and deal
231 with it appropriately.
233 You also don't get the L<Moose::Object> constructor, and therefore attribute
234 initialization will not work as normally expected. If you want to use Moose
235 attributes, then they need to be made lazy to correctly initialize.
237 Note that this only applies if your component needs to maintain component
238 backwards compatibility for Catalyst versions before 5.71001 - in 5.71001
239 attributes work as expected, and the BUILD method is called normally
240 (although BUILDARGS is not).
242 If you depend on Catalyst 5.8, then B<all> Moose features work as expected.
244 You will also see this issue if you do the following:
246 package TestApp::Controller::Example;
248 use base 'Catalyst::Controller';
250 as C< use base > appends to @ISA.
252 =head3 use Moose in MyApp
254 Similar to the above, this will also fail:
263 If you need to use Moose in your application class (e.g. for method modifiers
264 etc.) then the correct technique is:
272 __PACKAGE__->config( name => 'MyApp' );
273 __PACKAGE__->setup(qw/
277 =head2 Anonymous closures installed directly into the symbol table
279 If you have any code which installs anonymous subroutine references directly
280 into the symbol table, you may encounter breakages. The simplest solution is
281 to use L<Sub::Name> to name the subroutine. Example:
283 # Original code, likely to break:
284 my $full_method_name = join('::', $package_name, $method_name);
285 *$full_method_name = sub { ... };
288 use Sub::Name 'subname';
289 my $full_method_name = join('::',$package_name, $method_name);
290 *$full_method_name = subname $full_method_name, sub { ... };
292 Additionally, you can take advantage of Catalyst's use of L<Class::MOP> and
293 install the closure using the appropriate metaclass. Example:
296 my $metaclass = Moose::Meta::Class->initialize($package_name);
297 $metaclass->add_method($method_name => sub { ... });
299 =head2 Hooking into application setup
301 To execute code during application start-up, the following snippet in MyApp.pm
305 my ($class, @args) = @_;
306 $class->NEXT::setup(@args);
307 ... # things to do after the actual setup
310 With Catalyst 5.80 this won't work anymore, because Catalyst no longer
311 uses NEXT.pm for method resolution. The functionality was only ever
312 originally operational as L<NEXT> remembers what methods have already
313 been called, and will not call them again.
315 Using this now causes infinite recursion between MyApp::setup and
316 Catalyst::setup, due to other backwards compatibility issues related to how
317 plugin setup works. Moose method modifiers like C<< before|after|around setup
318 => sub { ... }; >> also will not operate correctly on the setup method.
320 The right way to do it is this:
322 after setup_finalize => sub {
323 ... # things to do after the actual setup
326 The setup_finalize hook was introduced as a way to avoid this issue.
328 =head2 Components with a new method which returns false
330 Previously, if you had a component which inherited from Catalyst::COMPONENT,
331 but overrode the new method to return false, then your class's configuration
332 would be blessed into a hash on your behalf, and this would be returned from
333 the COMPONENT method.
335 This behavior makes no sense, and so has been removed. Implementing your own
336 C< new > method in components is B<highly> discouraged. Instead, you should
337 inherit the new method from Catalyst::Component, and use Moose's BUILD
338 functionality and/or Moose attributes to perform any construction work
339 necessary for your class.
341 =head2 __PACKAGE__->mk_accessor('meta');
343 Won't work due to a limitation of L<Moose>. This is currently being fixed
346 =head2 Class::Data::Inheritable side effects
348 Previously, writing to a class data accessor would copy the accessor method
349 down into your package.
351 This behavior has been removed. While the class data is still stored
352 per-class, it is stored on the metaclass of the class defining the accessor.
354 Therefore anything relying on the side effect of the accessor being copied down
357 The following test demonstrates the problem:
361 use base qw/Class::Data::Inheritable/;
362 __PACKAGE__->mk_classdata('foo');
367 use base qw/BaseClass/;
370 BaseClass->foo('base class');
371 Child->foo('sub class');
374 isnt(BaseClass->can('foo'), Child->can('foo'));
376 =head2 Extending Catalyst::Request or other classes in an ad-hoc manner using mk_accessors
378 Previously, it was possible to add additional accessors to Catalyst::Request
379 (or other classes) by calling the mk_accessors class method.
381 This is no longer supported - users should make a subclass of the class whose
382 behavior they would like to change, rather than globally polluting the
385 =head2 Confused multiple inheritance with Catalyst::Component::COMPONENT
387 Previously, Catalyst's COMPONENT method would delegate to the method on
388 the right hand side, which could then delegate back again with
389 NEXT. This is poor practice, and in addition, makes no sense with C3
390 method dispatch order, and is therefore no longer supported.
392 If a COMPONENT method is detected in the inheritance hierarchy to the right
393 hand side of Catalyst::Component::COMPONENT, then the following warning
394 message will be emitted:
396 There is a COMPONENT method resolving after Catalyst::Component
399 The correct fix is to re-arrange your class's inheritance hierarchy so that the
400 COMPONENT method you would like to inherit is the first (left-hand most)
401 COMPONENT method in your @ISA.
405 =head2 Actions in your application class
407 Having actions in your application class will now emit a warning at application
408 startup as this is deprecated. It is highly recommended that these actions are moved
409 into a MyApp::Controller::Root (as demonstrated by the scaffold application
410 generated by catalyst.pl).
412 This warning, also affects tests. You should move actions in your test,
413 creating a myTest::Controller::Root, like the following example:
415 package MyTest::Controller::Root;
420 use parent 'Catalyst::Controller';
422 __PACKAGE__->config(namespace => '');
425 my ( $self, $c ) = @_;
431 =head2 ::[MVC]:: naming scheme
433 Having packages called MyApp::[MVC]::XX is deprecated and can no longer be generated
436 This is still supported, but it is recommended that you rename your application
437 components to Model/View/Controller.
439 A warning will be issued at application startup if the ::[MVC]:: naming scheme is
442 =head2 Catalyst::Base
444 Any code using L<Catalyst::Base> will now emit a warning; this
445 module will be removed in a future release.
447 =head2 Methods in Catalyst::Dispatcher
449 The following methods in Catalyst::Dispatcher are implementation
450 details, which may change in the 5.8X release series, and therefore their use
451 is highly deprecated.
459 =item registered_dispatch_types
461 =item method_action_class
469 The first time one of these methods is called, a warning will be emitted:
471 Class $class is calling the deprecated method Catalyst::Dispatcher::$public_method_name,
472 this will be removed in Catalyst 5.9X
474 You should B<NEVER> be calling any of these methods from application code.
476 Plugin authors and maintainers whose plugins currently call these methods
477 should change to using the public API, or, if you do not feel the public API
478 adequately supports your use case, please email the development list to
479 discuss what API features you need so that you can be appropriately supported.
481 =head2 Class files with names that don't correspond to the packages they define
483 In this version of Catalyst, if a component is loaded from disk, but no
484 symbols are defined in that component's name space after it is loaded, this
485 warning will be issued:
487 require $class was successful but the package is not defined.
489 This is to protect against confusing bugs caused by mistyping package names,
490 and will become a fatal error in a future version.
492 Please note that 'inner packages' (via L<Devel::InnerPackage>) are still fully
493 supported; this warning is only issued when component file naming does not map
494 to B<any> of the packages defined within that component.
496 =head2 $c->plugin method
498 Calling the plugin method is deprecated, and calling it at run time is B<highly
501 Instead you are recommended to use L<Catalyst::Model::Adaptor> or similar to
502 compose the functionality you need outside of the main application name space.
504 Calling the plugin method will not be supported past Catalyst 5.81.