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. Documentation about how to
19 take advantage of L<Plack::Middleware> by writing your own C<< .psgi >> file
20 is contained in L<Catalyst::PSGI>.
22 If you have created a custom subclass of L<Catalyst:Engine> you will need to
23 convert it to be a subclass of L<Plack::Handler>.
25 If you are using the L<Plack> engine, L<Catalyst::Engine::PSGI>, this new
26 release supercedes that code.
28 If you are using a subclass of L<Catalyst::Engine> that is aimed at nonstandard
29 or internal / testing uses, such as L<Catalyst::Engine::Embeddable> you should
30 still be able to continue using that engine.
32 Advice for specific subclasses of L<Catalyst::Engine> follows:
34 =head2 Upgrading the FastCGI Engine
36 No upgrade needed if your myapp_fastcgi.pl script is already upgraded
37 enough to use L<Catalyst::Script::FastCGI>.
39 =head2 Upgrading the mod_perl / Apache Engines
41 The engines that are build upon the various iterations of mod_perl,
42 L<Catalyst::Engine::Apache::MP13> and
43 L<Catalyst::Engine::Apache2::MP20> should be seemless upgrades and will
44 work using using L<Plack::Handler::Apache1> or L<Plack::Handler::Apache2>
47 L<Catalyst::Engine::Apache2::MP19>, is however no longer supported, as Plack
48 does not support mod_perl version 1.99
50 =head2 Upgrading the HTTP Engine
52 The default development server that comes with the L<Catalyst> distribution
53 should continue to work as expected with no changes as long as your C<myapp_server>
54 script is upgraded to use L<Catalyst::Script::HTTP>.
56 =head2 Upgrading the CGI Engine
58 If you were using L<Catalyst::Engine::CGI> there is no upgrade needed if your
59 myapp_cgi.pl script is already upgraded enough to use L<Catalyst::Script::CGI>.
61 =head2 Upgrading the Preforking Engine
63 If you were using L<Catalyst::Engine::HTTP::Prefork> then L<Starman>
64 is automatically loaded.
66 If you were customising your server script to pass opttions to the prefork engine,
67 then this is no longer supported. The recommended route to implement this functionality
68 is to write a simple .psgi file for your application, then use the L<plackup> untility.
70 =head2 Upgrading the PSGI Engine
72 If you were using L<Catalyst::Engine::PSGI> this new release supercedes this
73 engine in supporting L<Plack>. By default the Engine is now always L<Plack>.
74 As a result, you can stop depending on L<Catalyst::Engine::PSGI> in your
77 Applications that were using L<Catalyst::Engine::PSGI>
78 previously should entirely continue to work in this release with no changes.
80 However, if you have an C<app.psgi> script, then you no longer
81 need to specify the PSGI engine. Instead, the L<Catalyst> application class
82 now has a new method C<psgi_app> which returns a L<PSGI> compatible coderef
83 which you can wrap in middleware of your choice.
85 Catalyst will use the .psgi for your application if it is located in the C<home>
86 directory of the application
88 For example, if you were using L<Catalyst::Engine::PSGI> in the past, you will
89 have written (or generated) a C<script/myapp.psgi> file similar to this one:
94 MyCatalystApp->setup_engine('PSGI');
97 enable ... # enable your desired middleware
98 sub { MyCatalystApp->run(@_) };
101 Instead, you now say:
107 enable ... #enable your desired middleware
108 MyCatalystApp->psgi_app;
111 In the simplest case:
113 MyCatalystApp->setup_engine('PSGI');
114 my $app = sub { MyCatalystApp->run(@_) }
118 MyCatalystApp->setup_engine('PSGI');
119 my $app = MyCatalystApp->psgi_app(@_);
123 my $app = sub { MyCatalystApp->psgi_app(@_) };
124 # If you make ^^ this mistake, your app won't work, and will confuse the hell out of you!
126 You can now rename C<< script/myapp.psgi >> to C<< myapp.psgi >>, and the built-in
127 Catalyst scripts, and your test suite will start using your .psgi file.
129 B<NOTE:> If you rename your .psgi file without these modifications, then any tests run via
130 L<Catalyst::Test> will not be compatible with the new release, and will result in
131 the development server starting, rather than the expected test running.
133 =head2 Engines which are known broken
135 The following engines B<DO NOT> work as of Catalyst version 5.90. The core
136 team is extremely happy to work with the developers and/or users of these
137 engines to help them port to the new Plack/Engine system, however applications
138 which are currently using these engines B<WILL NOT> run without modification
143 =item Catalyst::Engine::Wx
145 =item Catalyst::Engine::Zeus
147 =item Catalyst::Engine::JobQueue::POE
149 =item Catalyst::Engine::XMPP2
151 =item Catalyst::Engine::SCGI
155 =head2 Engines with unknown status
157 The following engines have untested or unknown compatibility. Reports are
162 =item Catalyst::Engine::Mojo
164 =item Catalyst::Engine::Server (Marked as Deprecated)
166 =item Catalyst::Engine::HTTP::POE (Marked as Deprecated)
170 =head2 Specifying the engine in the call to ->setup
174 =head2 Plack functionality
176 See L<Catalyst::PSGI>.
180 Tests should generally work the same in Catalyst 5.89, however there are some differences.
182 Previously, if using L<Catalyst::Test> and doing local requests (against a local server),
183 if the application threw an exception then this exception propagated into the test.
185 This behaviour has been removed, and now a 500 response will be returned to the test.
186 This change unifies behaviour, to make local test requests behave similarly to remote
189 =head1 Upgrading to Catalyst 5.80
191 Most applications and plugins should run unaltered on Catalyst 5.80.
193 However, a lot of refactoring work has taken place, and several changes have
194 been made which could cause incompatibilities. If your application or plugin
195 is using deprecated code, or relying on side effects, then you could have
196 issues upgrading to this release.
198 Most issues found with pre-existing components have been easy to
199 solve. This document provides a complete description of behavior changes
200 which may cause compatibility issues, and of new Catalyst warnings which
203 If you think you have found an upgrade-related issue which is not covered in
204 this document, please email the Catalyst list to discuss the problem.
206 =head1 Moose features
208 =head2 Application class roles
210 You can only apply method modifiers after the application's C<< ->setup >>
211 method has been called. This means that modifiers will not work with methods
212 which run during the call to C<< ->setup >>.
214 See L<Catalyst::Manual::ExtendingCatalyst> for more information about using
215 L<Moose> in your applications.
217 =head2 Controller actions in Moose roles
219 You can use L<MooseX::MethodAttributes::Role> if you want to declare actions
222 =head2 Using Moose in Components
224 The correct way to use Moose in a component in a both forward and backwards
227 package TestApp::Controller::Root;
229 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
231 See L<Components which inherit from Moose::Object before Catalyst::Component>.
233 =head1 Known backwards compatibility breakages
235 =head2 Applications in a single file
237 Applications must be in their own file, and loaded at compile time. This
238 issue generally only affects the tests of CPAN distributions. Your
239 application will fail if you try to define an application inline in a
240 block, and use plugins which supply a C< new > method, then use that
241 application latter in tests within the same file.
243 This is due to the fact that Catalyst is inlining a new method on your
244 application class allowing it to be compatible with Moose. The method
245 used to do this changed in 5.80004 to avoid the possibility of reporting
246 an 'Unknown Error' if your application failed to compile.
248 =head2 Issues with Class::C3
250 Catalyst 5.80 uses the L<Algorithm::C3> method dispatch order. This is
251 built into Perl 5.10, and comes via L<Class::C3> for Perl 5.8. This
252 replaces L<NEXT> with L<Class::C3::Adopt::NEXT>, forcing all components
253 to resolve methods using C3, rather than the unpredictable dispatch
256 This issue is characterised by your application failing to start due to an
257 error message about having a non-linear @ISA.
259 The Catalyst plugin most often causing this is
260 L<Catalyst::Plugin::Session::Store::FastMmap> - if you are using this
261 plugin and see issues, then please upgrade your plugins, as it has been
262 fixed. Note that Makefile.PL in the distribution will warn about known
263 incompatible components.
265 This issue can, however, be found in your own application - the only solution is
266 to go through each base class of the class the error was reported against, until
267 you identify the ones in conflict, and resolve them.
269 To be able to generate a linear @ISA, the list of superclasses for each
270 class must be resolvable using the C3 algorithm. Unfortunately, when
271 superclasses are being used as mixins (to add functionality used in your class),
272 and with multiple inheritance, it is easy to get this wrong.
274 Most common is the case of:
276 package Component1; # Note, this is the common case
277 use base qw/Class::Accessor::Fast Class::Data::Inheritable/;
279 package Component2; # Accidentally saying it this way causes a failure
280 use base qw/Class::Data::Inheritable Class::Accessor::Fast/;
283 use base qw/Component1 Component2/;
285 Any situation like this will cause your application to fail to start.
287 For additional documentation about this issue, and how to resolve it, see
288 L<Class::C3::Adopt::NEXT>.
290 =head2 Components which inherit from Moose::Object before Catalyst::Component
292 Moose components which say:
294 package TestApp::Controller::Example;
296 extends qw/Moose::Object Catalyst::Component/;
298 to use the constructor provided by Moose, while working (if you do some hacks
299 with the C< BUILDARGS > method), will not work with Catalyst 5.80 as
300 C<Catalyst::Component> inherits from C<Moose::Object>, and so C< @ISA > fails
303 The correct way to use Moose in a component in a both forward and backwards
306 package TestApp::Controller::Root;
308 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
310 Note that the C< extends > declaration needs to occur in a begin block for
311 L<attributes> to operate correctly.
313 This way you do not inherit directly from C<Moose::Object>
314 yourself. Having components which do not inherit their constructor from
315 C<Catalyst::Component> is B<unsupported>, and has never been recommended,
316 therefore you're on your own if you're using this technique. You'll need
317 to detect the version of Catalyst your application is running, and deal
318 with it appropriately.
320 You also don't get the L<Moose::Object> constructor, and therefore attribute
321 initialization will not work as normally expected. If you want to use Moose
322 attributes, then they need to be made lazy to correctly initialize.
324 Note that this only applies if your component needs to maintain component
325 backwards compatibility for Catalyst versions before 5.71001 - in 5.71001
326 attributes work as expected, and the BUILD method is called normally
327 (although BUILDARGS is not).
329 If you depend on Catalyst 5.8, then B<all> Moose features work as expected.
331 You will also see this issue if you do the following:
333 package TestApp::Controller::Example;
335 use base 'Catalyst::Controller';
337 as C< use base > appends to @ISA.
339 =head3 use Moose in MyApp
341 Similar to the above, this will also fail:
350 If you need to use Moose in your application class (e.g. for method modifiers
351 etc.) then the correct technique is:
359 __PACKAGE__->config( name => 'MyApp' );
360 __PACKAGE__->setup(qw/
364 =head2 Anonymous closures installed directly into the symbol table
366 If you have any code which installs anonymous subroutine references directly
367 into the symbol table, you may encounter breakages. The simplest solution is
368 to use L<Sub::Name> to name the subroutine. Example:
370 # Original code, likely to break:
371 my $full_method_name = join('::', $package_name, $method_name);
372 *$full_method_name = sub { ... };
375 use Sub::Name 'subname';
376 my $full_method_name = join('::',$package_name, $method_name);
377 *$full_method_name = subname $full_method_name, sub { ... };
379 Additionally, you can take advantage of Catalyst's use of L<Class::MOP> and
380 install the closure using the appropriate metaclass. Example:
383 my $metaclass = Moose::Meta::Class->initialize($package_name);
384 $metaclass->add_method($method_name => sub { ... });
386 =head2 Hooking into application setup
388 To execute code during application start-up, the following snippet in MyApp.pm
392 my ($class, @args) = @_;
393 $class->NEXT::setup(@args);
394 ... # things to do after the actual setup
397 With Catalyst 5.80 this won't work anymore, because Catalyst no longer
398 uses NEXT.pm for method resolution. The functionality was only ever
399 originally operational as L<NEXT> remembers what methods have already
400 been called, and will not call them again.
402 Using this now causes infinite recursion between MyApp::setup and
403 Catalyst::setup, due to other backwards compatibility issues related to how
404 plugin setup works. Moose method modifiers like C<< before|after|around setup
405 => sub { ... }; >> also will not operate correctly on the setup method.
407 The right way to do it is this:
409 after setup_finalize => sub {
410 ... # things to do after the actual setup
413 The setup_finalize hook was introduced as a way to avoid this issue.
415 =head2 Components with a new method which returns false
417 Previously, if you had a component which inherited from Catalyst::COMPONENT,
418 but overrode the new method to return false, then your class's configuration
419 would be blessed into a hash on your behalf, and this would be returned from
420 the COMPONENT method.
422 This behavior makes no sense, and so has been removed. Implementing your own
423 C< new > method in components is B<highly> discouraged. Instead, you should
424 inherit the new method from Catalyst::Component, and use Moose's BUILD
425 functionality and/or Moose attributes to perform any construction work
426 necessary for your class.
428 =head2 __PACKAGE__->mk_accessor('meta');
430 Won't work due to a limitation of L<Moose>. This is currently being fixed
433 =head2 Class::Data::Inheritable side effects
435 Previously, writing to a class data accessor would copy the accessor method
436 down into your package.
438 This behavior has been removed. While the class data is still stored
439 per-class, it is stored on the metaclass of the class defining the accessor.
441 Therefore anything relying on the side effect of the accessor being copied down
444 The following test demonstrates the problem:
448 use base qw/Class::Data::Inheritable/;
449 __PACKAGE__->mk_classdata('foo');
454 use base qw/BaseClass/;
457 BaseClass->foo('base class');
458 Child->foo('sub class');
461 isnt(BaseClass->can('foo'), Child->can('foo'));
463 =head2 Extending Catalyst::Request or other classes in an ad-hoc manner using mk_accessors
465 Previously, it was possible to add additional accessors to Catalyst::Request
466 (or other classes) by calling the mk_accessors class method.
468 This is no longer supported - users should make a subclass of the class whose
469 behavior they would like to change, rather than globally polluting the
472 =head2 Confused multiple inheritance with Catalyst::Component::COMPONENT
474 Previously, Catalyst's COMPONENT method would delegate to the method on
475 the right hand side, which could then delegate back again with
476 NEXT. This is poor practice, and in addition, makes no sense with C3
477 method dispatch order, and is therefore no longer supported.
479 If a COMPONENT method is detected in the inheritance hierarchy to the right
480 hand side of Catalyst::Component::COMPONENT, then the following warning
481 message will be emitted:
483 There is a COMPONENT method resolving after Catalyst::Component
486 The correct fix is to re-arrange your class's inheritance hierarchy so that the
487 COMPONENT method you would like to inherit is the first (left-hand most)
488 COMPONENT method in your @ISA.
492 =head2 Actions in your application class
494 Having actions in your application class will now emit a warning at application
495 startup as this is deprecated. It is highly recommended that these actions are moved
496 into a MyApp::Controller::Root (as demonstrated by the scaffold application
497 generated by catalyst.pl).
499 This warning, also affects tests. You should move actions in your test,
500 creating a myTest::Controller::Root, like the following example:
502 package MyTest::Controller::Root;
507 use parent 'Catalyst::Controller';
509 __PACKAGE__->config(namespace => '');
512 my ( $self, $c ) = @_;
518 =head2 ::[MVC]:: naming scheme
520 Having packages called MyApp::[MVC]::XX is deprecated and can no longer be generated
523 This is still supported, but it is recommended that you rename your application
524 components to Model/View/Controller.
526 A warning will be issued at application startup if the ::[MVC]:: naming scheme is
529 =head2 Catalyst::Base
531 Any code using L<Catalyst::Base> will now emit a warning; this
532 module will be removed in a future release.
534 =head2 Methods in Catalyst::Dispatcher
536 The following methods in Catalyst::Dispatcher are implementation
537 details, which may change in the 5.8X release series, and therefore their use
538 is highly deprecated.
546 =item registered_dispatch_types
548 =item method_action_class
556 The first time one of these methods is called, a warning will be emitted:
558 Class $class is calling the deprecated method Catalyst::Dispatcher::$public_method_name,
559 this will be removed in Catalyst 5.9X
561 You should B<NEVER> be calling any of these methods from application code.
563 Plugin authors and maintainers whose plugins currently call these methods
564 should change to using the public API, or, if you do not feel the public API
565 adequately supports your use case, please email the development list to
566 discuss what API features you need so that you can be appropriately supported.
568 =head2 Class files with names that don't correspond to the packages they define
570 In this version of Catalyst, if a component is loaded from disk, but no
571 symbols are defined in that component's name space after it is loaded, this
572 warning will be issued:
574 require $class was successful but the package is not defined.
576 This is to protect against confusing bugs caused by mistyping package names,
577 and will become a fatal error in a future version.
579 Please note that 'inner packages' (via L<Devel::InnerPackage>) are still fully
580 supported; this warning is only issued when component file naming does not map
581 to B<any> of the packages defined within that component.
583 =head2 $c->plugin method
585 Calling the plugin method is deprecated, and calling it at run time is B<highly
588 Instead you are recommended to use L<Catalyst::Model::Adaptor> or similar to
589 compose the functionality you need outside of the main application name space.
591 Calling the plugin method will not be supported past Catalyst 5.81.