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??? FIXME - is this true?
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 XXX FIXME - note how to run Starman with different options.
68 =head2 Upgrading the PSGI Engine
70 If you were using L<Catalyst::Engine::PSGI> this new release supercedes this
71 engine in supporting L<Plack>. By default the Engine is now always L<Plack>.
72 As a result, you can stop depending on L<Catalyst::Engine::PSGI> in your
75 Applications that were using L<Catalyst::Engine::PSGI>
76 previously should entirely continue to work in this release with no changes.
78 However, if you have an C<app.psgi> script, then you no longer
79 need to specify the PSGI engine. Instead, the L<Catalyst> application class
80 now has a new method C<psgi_app> which returns a L<PSGI> compatible coderef
81 which you can wrap in middleware of your choice.
83 Catalyst will use the .psgi for your application if it is located in the C<home>
84 directory of the application
86 For example, if you were using L<Catalyst::Engine::PSGI> in the past, you will
87 have written (or generated) a C<script/myapp.psgi> file similar to this one:
92 MyCatalystApp->setup_engine('PSGI');
95 enable ... # enable your desired middleware
96 sub { MyCatalystApp->run(@_) };
105 enable ... #enable your desired middleware
106 MyCatalystApp->psgi_app;
109 And also rename C<< script/myapp.psgi >> to C<< myapp.psgi >>.
111 XXX - FIXME - t/psgi_file_testapp_engine_psgi_compat.t
113 If you rename your .psgi file without these modifications, then any tests run via
114 L<Catalyst::Test> will not be compatible with the new release, and will result in
115 the development server starting, rather than the expected test running.
117 =head2 Engines which are known broken
119 The following engines B<DO NOT> work as of Catalyst version 5.90. The core
120 team is extremely happy to work with the developers and/or users of these
121 engines to help them port to the new Plack/Engine system, however applications
122 which are currently using these engines B<WILL NOT> run without modification
127 =item Catalyst::Engine::Wx
129 =item Catalyst::Engine::Zeus
131 =item Catalyst::Engine::JobQueue::POE
133 =item Catalyst::Engine::XMPP2
135 =item Catalyst::Engine::SCGI
139 =head2 Engines with unknown status
141 The following engines have untested or unknown compatibility. Reports are
146 =item Catalyst::Engine::Mojo
148 =item Catalyst::Engine::Server (Marked as Deprecated)
150 =item Catalyst::Engine::HTTP::POE (Marked as Deprecated)
154 =head2 Using middleware
156 XXX Should this be here or elsewhere?
158 =head2 Making an app.psgi file
160 =head2 Running with plackup?
162 =head1 Upgrading to Catalyst 5.80
164 Most applications and plugins should run unaltered on Catalyst 5.80.
166 However, a lot of refactoring work has taken place, and several changes have
167 been made which could cause incompatibilities. If your application or plugin
168 is using deprecated code, or relying on side effects, then you could have
169 issues upgrading to this release.
171 Most issues found with pre-existing components have been easy to
172 solve. This document provides a complete description of behavior changes
173 which may cause compatibility issues, and of new Catalyst warnings which
176 If you think you have found an upgrade-related issue which is not covered in
177 this document, please email the Catalyst list to discuss the problem.
179 =head1 Moose features
181 =head2 Application class roles
183 You can only apply method modifiers after the application's C<< ->setup >>
184 method has been called. This means that modifiers will not work with methods
185 which run during the call to C<< ->setup >>.
187 See L<Catalyst::Manual::ExtendingCatalyst> for more information about using
188 L<Moose> in your applications.
190 =head2 Controller actions in Moose roles
192 You can use L<MooseX::MethodAttributes::Role> if you want to declare actions
195 =head2 Using Moose in Components
197 The correct way to use Moose in a component in a both forward and backwards
200 package TestApp::Controller::Root;
202 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
204 See L<Components which inherit from Moose::Object before Catalyst::Component>.
206 =head1 Known backwards compatibility breakages
208 =head2 Applications in a single file
210 Applications must be in their own file, and loaded at compile time. This
211 issue generally only affects the tests of CPAN distributions. Your
212 application will fail if you try to define an application inline in a
213 block, and use plugins which supply a C< new > method, then use that
214 application latter in tests within the same file.
216 This is due to the fact that Catalyst is inlining a new method on your
217 application class allowing it to be compatible with Moose. The method
218 used to do this changed in 5.80004 to avoid the possibility of reporting
219 an 'Unknown Error' if your application failed to compile.
221 =head2 Issues with Class::C3
223 Catalyst 5.80 uses the L<Algorithm::C3> method dispatch order. This is
224 built into Perl 5.10, and comes via L<Class::C3> for Perl 5.8. This
225 replaces L<NEXT> with L<Class::C3::Adopt::NEXT>, forcing all components
226 to resolve methods using C3, rather than the unpredictable dispatch
229 This issue is characterised by your application failing to start due to an
230 error message about having a non-linear @ISA.
232 The Catalyst plugin most often causing this is
233 L<Catalyst::Plugin::Session::Store::FastMmap> - if you are using this
234 plugin and see issues, then please upgrade your plugins, as it has been
235 fixed. Note that Makefile.PL in the distribution will warn about known
236 incompatible components.
238 This issue can, however, be found in your own application - the only solution is
239 to go through each base class of the class the error was reported against, until
240 you identify the ones in conflict, and resolve them.
242 To be able to generate a linear @ISA, the list of superclasses for each
243 class must be resolvable using the C3 algorithm. Unfortunately, when
244 superclasses are being used as mixins (to add functionality used in your class),
245 and with multiple inheritence, it is easy to get this wrong.
247 Most common is the case of:
249 package Component1; # Note, this is the common case
250 use base qw/Class::Accessor::Fast Class::Data::Inheritable/;
252 package Component2; # Accidentally saying it this way causes a failure
253 use base qw/Class::Data::Inheritable Class::Accessor::Fast/;
256 use base qw/Component1 Component2/;
258 Any situation like this will cause your application to fail to start.
260 For additional documentation about this issue, and how to resolve it, see
261 L<Class::C3::Adopt::NEXT>.
263 =head2 Components which inherit from Moose::Object before Catalyst::Component
265 Moose components which say:
267 package TestApp::Controller::Example;
269 extends qw/Moose::Object Catalyst::Component/;
271 to use the constructor provided by Moose, while working (if you do some hacks
272 with the C< BUILDARGS > method), will not work with Catalyst 5.80 as
273 C<Catalyst::Component> inherits from C<Moose::Object>, and so C< @ISA > fails
276 The correct way to use Moose in a component in a both forward and backwards
279 package TestApp::Controller::Root;
281 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
283 Note that the C< extends > declaration needs to occur in a begin block for
284 L<attributes> to operate correctly.
286 This way you do not inherit directly from C<Moose::Object>
287 yourself. Having components which do not inherit their constructor from
288 C<Catalyst::Component> is B<unsupported>, and has never been recommended,
289 therefore you're on your own if you're using this technique. You'll need
290 to detect the version of Catalyst your application is running, and deal
291 with it appropriately.
293 You also don't get the L<Moose::Object> constructor, and therefore attribute
294 initialization will not work as normally expected. If you want to use Moose
295 attributes, then they need to be made lazy to correctly initialize.
297 Note that this only applies if your component needs to maintain component
298 backwards compatibility for Catalyst versions before 5.71001 - in 5.71001
299 attributes work as expected, and the BUILD method is called normally
300 (although BUILDARGS is not).
302 If you depend on Catalyst 5.8, then B<all> Moose features work as expected.
304 You will also see this issue if you do the following:
306 package TestApp::Controller::Example;
308 use base 'Catalyst::Controller';
310 as C< use base > appends to @ISA.
312 =head3 use Moose in MyApp
314 Similar to the above, this will also fail:
323 If you need to use Moose in your application class (e.g. for method modifiers
324 etc.) then the correct technique is:
332 __PACKAGE__->config( name => 'MyApp' );
333 __PACKAGE__->setup(qw/
337 =head2 Anonymous closures installed directly into the symbol table
339 If you have any code which installs anonymous subroutine references directly
340 into the symbol table, you may encounter breakages. The simplest solution is
341 to use L<Sub::Name> to name the subroutine. Example:
343 # Original code, likely to break:
344 my $full_method_name = join('::', $package_name, $method_name);
345 *$full_method_name = sub { ... };
348 use Sub::Name 'subname';
349 my $full_method_name = join('::',$package_name, $method_name);
350 *$full_method_name = subname $full_method_name, sub { ... };
352 Additionally, you can take advantage of Catalyst's use of L<Class::MOP> and
353 install the closure using the appropriate metaclass. Example:
356 my $metaclass = Moose::Meta::Class->initialize($package_name);
357 $metaclass->add_method($method_name => sub { ... });
359 =head2 Hooking into application setup
361 To execute code during application start-up, the following snippet in MyApp.pm
365 my ($class, @args) = @_;
366 $class->NEXT::setup(@args);
367 ... # things to do after the actual setup
370 With Catalyst 5.80 this won't work anymore, because Catalyst no longer
371 uses NEXT.pm for method resolution. The functionality was only ever
372 originally operational as L<NEXT> remembers what methods have already
373 been called, and will not call them again.
375 Using this now causes infinite recursion between MyApp::setup and
376 Catalyst::setup, due to other backwards compatibility issues related to how
377 plugin setup works. Moose method modifiers like C<< before|after|around setup
378 => sub { ... }; >> also will not operate correctly on the setup method.
380 The right way to do it is this:
382 after setup_finalize => sub {
383 ... # things to do after the actual setup
386 The setup_finalize hook was introduced as a way to avoid this issue.
388 =head2 Components with a new method which returns false
390 Previously, if you had a component which inherited from Catalyst::COMPONENT,
391 but overrode the new method to return false, then your class's configuration
392 would be blessed into a hash on your behalf, and this would be returned from
393 the COMPONENT method.
395 This behavior makes no sense, and so has been removed. Implementing your own
396 C< new > method in components is B<highly> discouraged. Instead, you should
397 inherit the new method from Catalyst::Component, and use Moose's BUILD
398 functionality and/or Moose attributes to perform any construction work
399 necessary for your class.
401 =head2 __PACKAGE__->mk_accessor('meta');
403 Won't work due to a limitation of L<Moose>. This is currently being fixed
406 =head2 Class::Data::Inheritable side effects
408 Previously, writing to a class data accessor would copy the accessor method
409 down into your package.
411 This behavior has been removed. While the class data is still stored
412 per-class, it is stored on the metaclass of the class defining the accessor.
414 Therefore anything relying on the side effect of the accessor being copied down
417 The following test demonstrates the problem:
421 use base qw/Class::Data::Inheritable/;
422 __PACKAGE__->mk_classdata('foo');
427 use base qw/BaseClass/;
430 BaseClass->foo('base class');
431 Child->foo('sub class');
434 isnt(BaseClass->can('foo'), Child->can('foo'));
436 =head2 Extending Catalyst::Request or other classes in an ad-hoc manner using mk_accessors
438 Previously, it was possible to add additional accessors to Catalyst::Request
439 (or other classes) by calling the mk_accessors class method.
441 This is no longer supported - users should make a subclass of the class whose
442 behavior they would like to change, rather than globally polluting the
445 =head2 Confused multiple inheritance with Catalyst::Component::COMPONENT
447 Previously, Catalyst's COMPONENT method would delegate to the method on
448 the right hand side, which could then delegate back again with
449 NEXT. This is poor practice, and in addition, makes no sense with C3
450 method dispatch order, and is therefore no longer supported.
452 If a COMPONENT method is detected in the inheritance hierarchy to the right
453 hand side of Catalyst::Component::COMPONENT, then the following warning
454 message will be emitted:
456 There is a COMPONENT method resolving after Catalyst::Component
459 The correct fix is to re-arrange your class's inheritance hierarchy so that the
460 COMPONENT method you would like to inherit is the first (left-hand most)
461 COMPONENT method in your @ISA.
465 =head2 Actions in your application class
467 Having actions in your application class will now emit a warning at application
468 startup as this is deprecated. It is highly recommended that these actions are moved
469 into a MyApp::Controller::Root (as demonstrated by the scaffold application
470 generated by catalyst.pl).
472 This warning, also affects tests. You should move actions in your test,
473 creating a myTest::Controller::Root, like the following example:
475 package MyTest::Controller::Root;
480 use parent 'Catalyst::Controller';
482 __PACKAGE__->config(namespace => '');
485 my ( $self, $c ) = @_;
491 =head2 ::[MVC]:: naming scheme
493 Having packages called MyApp::[MVC]::XX is deprecated and can no longer be generated
496 This is still supported, but it is recommended that you rename your application
497 components to Model/View/Controller.
499 A warning will be issued at application startup if the ::[MVC]:: naming scheme is
502 =head2 Catalyst::Base
504 Any code using L<Catalyst::Base> will now emit a warning; this
505 module will be removed in a future release.
507 =head2 Methods in Catalyst::Dispatcher
509 The following methods in Catalyst::Dispatcher are implementation
510 details, which may change in the 5.8X release series, and therefore their use
511 is highly deprecated.
519 =item registered_dispatch_types
521 =item method_action_class
529 The first time one of these methods is called, a warning will be emitted:
531 Class $class is calling the deprecated method Catalyst::Dispatcher::$public_method_name,
532 this will be removed in Catalyst 5.9X
534 You should B<NEVER> be calling any of these methods from application code.
536 Plugin authors and maintainers whose plugins currently call these methods
537 should change to using the public API, or, if you do not feel the public API
538 adequately supports your use case, please email the development list to
539 discuss what API features you need so that you can be appropriately supported.
541 =head2 Class files with names that don't correspond to the packages they define
543 In this version of Catalyst, if a component is loaded from disk, but no
544 symbols are defined in that component's name space after it is loaded, this
545 warning will be issued:
547 require $class was successful but the package is not defined.
549 This is to protect against confusing bugs caused by mistyping package names,
550 and will become a fatal error in a future version.
552 Please note that 'inner packages' (via L<Devel::InnerPackage>) are still fully
553 supported; this warning is only issued when component file naming does not map
554 to B<any> of the packages defined within that component.
556 =head2 $c->plugin method
558 Calling the plugin method is deprecated, and calling it at run time is B<highly
561 Instead you are recommended to use L<Catalyst::Model::Adaptor> or similar to
562 compose the functionality you need outside of the main application name space.
564 Calling the plugin method will not be supported past Catalyst 5.81.