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
71 C<Makefile.PL>. Additionally, if you have an C<app.psgi> script you no longer
72 need to specify the PSGI engine. Instead, the L<Catalyst> application class
73 now has a new method C<psgi_app> which returns a L<Plack> compatible coderef.
75 For example, if you were using L<Catalyst::Engine::PSGI> in the past, you will
76 have written (or generated) an C<app.psgi> file similar to this one:
81 MyCatalystApp->setup_engine('PSGI');
84 enable ... # enable your desired middleware
85 sub { MyCatalystApp->run(@_) };
88 Instead, you should now just do:
94 enable ... #enable your desired middleware
95 MyCatalystApp->raw_psgi_app;
98 Applications that were using and deploying via L<Catalyst::Engine::PSGI>
99 previously should entirely continue to work in this release with no changes,
100 however if you were using Catalyst::Engine::PSGI previously, then this is
101 not compatible with L<Catalyst::Test> in the new version, and instead of
102 running a test server
104 =head2 Engines which are known broken
106 The following engines B<DO NOT> work as of Catalyst version 5.90. The core
107 team is extremely happy to work with the developers and/or users of these
108 engines to help them port to the new Plack/Engine system, however applications
109 which are currently using these engines B<WILL NOT> run without modification
114 =item Catalyst::Engine::Wx
118 =head2 Engines with unknown status
120 The following engines have untested or unknown compatibility. Reports are
123 Catalyst::Engine::Embeddable - needs testing, should work?
124 Catalyst::Engine::XMPP2
125 Catalyst::Engine::SCGI
126 Catalyst::Engine::Mojo
127 Catalyst::Engine::Zeus - broken for ages
128 Catalyst::Engine::JobQueue::POE - broken for ages
129 Catalyst::Engine::Stomp - fixed
130 Catalyst::Engine::Server (Marked as Deprecated)
131 Catalyst::Engine::HTTP::POE (Marked as Deprecated)
133 =head2 Using middleware
135 XXX Should this be here or elsewhere?
137 =head2 Making an app.psgi file
139 =head2 Running with plackup?
141 =head1 Upgrading to Catalyst 5.80
143 Most applications and plugins should run unaltered on Catalyst 5.80.
145 However, a lot of refactoring work has taken place, and several changes have
146 been made which could cause incompatibilities. If your application or plugin
147 is using deprecated code, or relying on side effects, then you could have
148 issues upgrading to this release.
150 Most issues found with pre-existing components have been easy to
151 solve. This document provides a complete description of behavior changes
152 which may cause compatibility issues, and of new Catalyst warnings which
155 If you think you have found an upgrade-related issue which is not covered in
156 this document, please email the Catalyst list to discuss the problem.
158 =head1 Moose features
160 =head2 Application class roles
162 You can only apply method modifiers after the application's C<< ->setup >>
163 method has been called. This means that modifiers will not work with methods
164 which run during the call to C<< ->setup >>.
166 See L<Catalyst::Manual::ExtendingCatalyst> for more information about using
167 L<Moose> in your applications.
169 =head2 Controller actions in Moose roles
171 You can use L<MooseX::MethodAttributes::Role> if you want to declare actions
174 =head2 Using Moose in Components
176 The correct way to use Moose in a component in a both forward and backwards
179 package TestApp::Controller::Root;
181 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
183 See L<Components which inherit from Moose::Object before Catalyst::Component>.
185 =head1 Known backwards compatibility breakages
187 =head2 Applications in a single file
189 Applications must be in their own file, and loaded at compile time. This
190 issue generally only affects the tests of CPAN distributions. Your
191 application will fail if you try to define an application inline in a
192 block, and use plugins which supply a C< new > method, then use that
193 application latter in tests within the same file.
195 This is due to the fact that Catalyst is inlining a new method on your
196 application class allowing it to be compatible with Moose. The method
197 used to do this changed in 5.80004 to avoid the possibility of reporting
198 an 'Unknown Error' if your application failed to compile.
200 =head2 Issues with Class::C3
202 Catalyst 5.80 uses the L<Algorithm::C3> method dispatch order. This is
203 built into Perl 5.10, and comes via L<Class::C3> for Perl 5.8. This
204 replaces L<NEXT> with L<Class::C3::Adopt::NEXT>, forcing all components
205 to resolve methods using C3, rather than the unpredictable dispatch
208 This issue is characterised by your application failing to start due to an
209 error message about having a non-linear @ISA.
211 The Catalyst plugin most often causing this is
212 L<Catalyst::Plugin::Session::Store::FastMmap> - if you are using this
213 plugin and see issues, then please upgrade your plugins, as it has been
214 fixed. Note that Makefile.PL in the distribution will warn about known
215 incompatible components.
217 This issue can, however, be found in your own application - the only solution is
218 to go through each base class of the class the error was reported against, until
219 you identify the ones in conflict, and resolve them.
221 To be able to generate a linear @ISA, the list of superclasses for each
222 class must be resolvable using the C3 algorithm. Unfortunately, when
223 superclasses are being used as mixins (to add functionality used in your class),
224 and with multiple inheritence, it is easy to get this wrong.
226 Most common is the case of:
228 package Component1; # Note, this is the common case
229 use base qw/Class::Accessor::Fast Class::Data::Inheritable/;
231 package Component2; # Accidentally saying it this way causes a failure
232 use base qw/Class::Data::Inheritable Class::Accessor::Fast/;
235 use base qw/Component1 Component2/;
237 Any situation like this will cause your application to fail to start.
239 For additional documentation about this issue, and how to resolve it, see
240 L<Class::C3::Adopt::NEXT>.
242 =head2 Components which inherit from Moose::Object before Catalyst::Component
244 Moose components which say:
246 package TestApp::Controller::Example;
248 extends qw/Moose::Object Catalyst::Component/;
250 to use the constructor provided by Moose, while working (if you do some hacks
251 with the C< BUILDARGS > method), will not work with Catalyst 5.80 as
252 C<Catalyst::Component> inherits from C<Moose::Object>, and so C< @ISA > fails
255 The correct way to use Moose in a component in a both forward and backwards
258 package TestApp::Controller::Root;
260 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
262 Note that the C< extends > declaration needs to occur in a begin block for
263 L<attributes> to operate correctly.
265 This way you do not inherit directly from C<Moose::Object>
266 yourself. Having components which do not inherit their constructor from
267 C<Catalyst::Component> is B<unsupported>, and has never been recommended,
268 therefore you're on your own if you're using this technique. You'll need
269 to detect the version of Catalyst your application is running, and deal
270 with it appropriately.
272 You also don't get the L<Moose::Object> constructor, and therefore attribute
273 initialization will not work as normally expected. If you want to use Moose
274 attributes, then they need to be made lazy to correctly initialize.
276 Note that this only applies if your component needs to maintain component
277 backwards compatibility for Catalyst versions before 5.71001 - in 5.71001
278 attributes work as expected, and the BUILD method is called normally
279 (although BUILDARGS is not).
281 If you depend on Catalyst 5.8, then B<all> Moose features work as expected.
283 You will also see this issue if you do the following:
285 package TestApp::Controller::Example;
287 use base 'Catalyst::Controller';
289 as C< use base > appends to @ISA.
291 =head3 use Moose in MyApp
293 Similar to the above, this will also fail:
302 If you need to use Moose in your application class (e.g. for method modifiers
303 etc.) then the correct technique is:
311 __PACKAGE__->config( name => 'MyApp' );
312 __PACKAGE__->setup(qw/
316 =head2 Anonymous closures installed directly into the symbol table
318 If you have any code which installs anonymous subroutine references directly
319 into the symbol table, you may encounter breakages. The simplest solution is
320 to use L<Sub::Name> to name the subroutine. Example:
322 # Original code, likely to break:
323 my $full_method_name = join('::', $package_name, $method_name);
324 *$full_method_name = sub { ... };
327 use Sub::Name 'subname';
328 my $full_method_name = join('::',$package_name, $method_name);
329 *$full_method_name = subname $full_method_name, sub { ... };
331 Additionally, you can take advantage of Catalyst's use of L<Class::MOP> and
332 install the closure using the appropriate metaclass. Example:
335 my $metaclass = Moose::Meta::Class->initialize($package_name);
336 $metaclass->add_method($method_name => sub { ... });
338 =head2 Hooking into application setup
340 To execute code during application start-up, the following snippet in MyApp.pm
344 my ($class, @args) = @_;
345 $class->NEXT::setup(@args);
346 ... # things to do after the actual setup
349 With Catalyst 5.80 this won't work anymore, because Catalyst no longer
350 uses NEXT.pm for method resolution. The functionality was only ever
351 originally operational as L<NEXT> remembers what methods have already
352 been called, and will not call them again.
354 Using this now causes infinite recursion between MyApp::setup and
355 Catalyst::setup, due to other backwards compatibility issues related to how
356 plugin setup works. Moose method modifiers like C<< before|after|around setup
357 => sub { ... }; >> also will not operate correctly on the setup method.
359 The right way to do it is this:
361 after setup_finalize => sub {
362 ... # things to do after the actual setup
365 The setup_finalize hook was introduced as a way to avoid this issue.
367 =head2 Components with a new method which returns false
369 Previously, if you had a component which inherited from Catalyst::COMPONENT,
370 but overrode the new method to return false, then your class's configuration
371 would be blessed into a hash on your behalf, and this would be returned from
372 the COMPONENT method.
374 This behavior makes no sense, and so has been removed. Implementing your own
375 C< new > method in components is B<highly> discouraged. Instead, you should
376 inherit the new method from Catalyst::Component, and use Moose's BUILD
377 functionality and/or Moose attributes to perform any construction work
378 necessary for your class.
380 =head2 __PACKAGE__->mk_accessor('meta');
382 Won't work due to a limitation of L<Moose>. This is currently being fixed
385 =head2 Class::Data::Inheritable side effects
387 Previously, writing to a class data accessor would copy the accessor method
388 down into your package.
390 This behavior has been removed. While the class data is still stored
391 per-class, it is stored on the metaclass of the class defining the accessor.
393 Therefore anything relying on the side effect of the accessor being copied down
396 The following test demonstrates the problem:
400 use base qw/Class::Data::Inheritable/;
401 __PACKAGE__->mk_classdata('foo');
406 use base qw/BaseClass/;
409 BaseClass->foo('base class');
410 Child->foo('sub class');
413 isnt(BaseClass->can('foo'), Child->can('foo'));
415 =head2 Extending Catalyst::Request or other classes in an ad-hoc manner using mk_accessors
417 Previously, it was possible to add additional accessors to Catalyst::Request
418 (or other classes) by calling the mk_accessors class method.
420 This is no longer supported - users should make a subclass of the class whose
421 behavior they would like to change, rather than globally polluting the
424 =head2 Confused multiple inheritance with Catalyst::Component::COMPONENT
426 Previously, Catalyst's COMPONENT method would delegate to the method on
427 the right hand side, which could then delegate back again with
428 NEXT. This is poor practice, and in addition, makes no sense with C3
429 method dispatch order, and is therefore no longer supported.
431 If a COMPONENT method is detected in the inheritance hierarchy to the right
432 hand side of Catalyst::Component::COMPONENT, then the following warning
433 message will be emitted:
435 There is a COMPONENT method resolving after Catalyst::Component
438 The correct fix is to re-arrange your class's inheritance hierarchy so that the
439 COMPONENT method you would like to inherit is the first (left-hand most)
440 COMPONENT method in your @ISA.
444 =head2 Actions in your application class
446 Having actions in your application class will now emit a warning at application
447 startup as this is deprecated. It is highly recommended that these actions are moved
448 into a MyApp::Controller::Root (as demonstrated by the scaffold application
449 generated by catalyst.pl).
451 This warning, also affects tests. You should move actions in your test,
452 creating a myTest::Controller::Root, like the following example:
454 package MyTest::Controller::Root;
459 use parent 'Catalyst::Controller';
461 __PACKAGE__->config(namespace => '');
464 my ( $self, $c ) = @_;
470 =head2 ::[MVC]:: naming scheme
472 Having packages called MyApp::[MVC]::XX is deprecated and can no longer be generated
475 This is still supported, but it is recommended that you rename your application
476 components to Model/View/Controller.
478 A warning will be issued at application startup if the ::[MVC]:: naming scheme is
481 =head2 Catalyst::Base
483 Any code using L<Catalyst::Base> will now emit a warning; this
484 module will be removed in a future release.
486 =head2 Methods in Catalyst::Dispatcher
488 The following methods in Catalyst::Dispatcher are implementation
489 details, which may change in the 5.8X release series, and therefore their use
490 is highly deprecated.
498 =item registered_dispatch_types
500 =item method_action_class
508 The first time one of these methods is called, a warning will be emitted:
510 Class $class is calling the deprecated method Catalyst::Dispatcher::$public_method_name,
511 this will be removed in Catalyst 5.9X
513 You should B<NEVER> be calling any of these methods from application code.
515 Plugin authors and maintainers whose plugins currently call these methods
516 should change to using the public API, or, if you do not feel the public API
517 adequately supports your use case, please email the development list to
518 discuss what API features you need so that you can be appropriately supported.
520 =head2 Class files with names that don't correspond to the packages they define
522 In this version of Catalyst, if a component is loaded from disk, but no
523 symbols are defined in that component's name space after it is loaded, this
524 warning will be issued:
526 require $class was successful but the package is not defined.
528 This is to protect against confusing bugs caused by mistyping package names,
529 and will become a fatal error in a future version.
531 Please note that 'inner packages' (via L<Devel::InnerPackage>) are still fully
532 supported; this warning is only issued when component file naming does not map
533 to B<any> of the packages defined within that component.
535 =head2 $c->plugin method
537 Calling the plugin method is deprecated, and calling it at run time is B<highly
540 Instead you are recommended to use L<Catalyst::Model::Adaptor> or similar to
541 compose the functionality you need outside of the main application name space.
543 Calling the plugin method will not be supported past Catalyst 5.81.