3 Catalyst::Upgrading - Instructions for upgrading to the latest Catalyst
5 =head1 Upgrading to Catalyst 5.80
7 Most applications and plugins should run unaltered on Catalyst 5.80.
9 However, a lot of refactoring work has taken place, and several changes have
10 been made which could cause incompatibilities. If your application or plugin
11 is using deprecated code, or relying on side effects, then you could have
12 issues upgrading to this release.
14 Most issues found with pre-existing components have been easy to
15 solve. This document provides a complete description of behavior changes
16 which may cause compatibility issues, and of new Catalyst warnings which
19 If you think you have found an upgrade-related issue which is not covered in
20 this document, please email the Catalyst list to discuss the problem.
24 =head2 Application class roles
26 You can only apply method modifiers after the application's C<< ->setup >>
27 method has been called. This means that modifiers will not work with methods
28 which run during the call to C<< ->setup >>.
30 See L<Catalyst::Manual::ExtendingCatalyst> for more information about using
31 L<Moose> in your applications.
33 =head2 Controller actions in Moose roles
35 You can use L<MooseX::MethodAttributes::Role> if you want to declare actions
38 =head2 Using Moose in Components
40 The correct way to use Moose in a component in a both forward and backwards
43 package TestApp::Controller::Root;
45 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
47 See L<Components which inherit from Moose::Object before Catalyst::Component>.
49 =head1 Known backwards compatibility breakages
51 =head2 Applications in a single file
53 Applications must be in their own file, and loaded at compile time. This
54 issue generally only affects the tests of CPAN distributions. Your
55 application will fail if you try to define an application inline in a
56 block, and use plugins which supply a C< new > method, then use that
57 application latter in tests within the same file.
59 This is due to the fact that Catalyst is inlining a new method on your
60 application class allowing it to be compatible with Moose. The method
61 used to do this changed in 5.80004 to avoid the possibility of reporting
62 an 'Unknown Error' if your application failed to compile.
64 =head2 Issues with Class::C3
66 Catalyst 5.80 uses the L<Algorithm::C3> method dispatch order. This is
67 built into Perl 5.10, and comes via L<Class::C3> for Perl 5.8. This
68 replaces L<NEXT> with L<Class::C3::Adopt::NEXT>, forcing all components
69 to resolve methods using C3, rather than the unpredictable dispatch
72 This issue is characterised by your application failing to start due to an
73 error message about having a non-linear @ISA.
75 The Catalyst plugin most often causing this is
76 L<Catalyst::Plugin::Session::Store::FastMmap> - if you are using this
77 plugin and see issues, then please upgrade your plugins, as it has been
78 fixed. Note that Makefile.PL in the distribution will warn about known
79 incompatible components.
81 This issue can, however, be found in your own application - the only solution is
82 to go through each base class of the class the error was reported against, until
83 you identify the ones in conflict, and resolve them.
85 To be able to generate a linear @ISA, the list of superclasses for each
86 class must be resolvable using the C3 algorithm. Unfortunately, when
87 superclasses are being used as mixins (to add functionality used in your class),
88 and with multiple inheritance, it is easy to get this wrong.
90 Most common is the case of:
92 package Component1; # Note, this is the common case
93 use base qw/Class::Accessor::Fast Class::Data::Inheritable/;
95 package Component2; # Accidentally saying it this way causes a failure
96 use base qw/Class::Data::Inheritable Class::Accessor::Fast/;
99 use base qw/Component1 Component2/;
101 Any situation like this will cause your application to fail to start.
103 For additional documentation about this issue, and how to resolve it, see
104 L<Class::C3::Adopt::NEXT>.
106 =head2 Components which inherit from Moose::Object before Catalyst::Component
108 Moose components which say:
110 package TestApp::Controller::Example;
112 extends qw/Moose::Object Catalyst::Component/;
114 to use the constructor provided by Moose, while working (if you do some hacks
115 with the C< BUILDARGS > method), will not work with Catalyst 5.80 as
116 C<Catalyst::Component> inherits from C<Moose::Object>, and so C< @ISA > fails
119 The correct way to use Moose in a component in a both forward and backwards
122 package TestApp::Controller::Root;
124 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
126 Note that the C< extends > declaration needs to occur in a begin block for
127 L<attributes> to operate correctly.
129 This way you do not inherit directly from C<Moose::Object>
130 yourself. Having components which do not inherit their constructor from
131 C<Catalyst::Component> is B<unsupported>, and has never been recommended,
132 therefore you're on your own if you're using this technique. You'll need
133 to detect the version of Catalyst your application is running, and deal
134 with it appropriately.
136 You also don't get the L<Moose::Object> constructor, and therefore attribute
137 initialization will not work as normally expected. If you want to use Moose
138 attributes, then they need to be made lazy to correctly initialize.
140 Note that this only applies if your component needs to maintain component
141 backwards compatibility for Catalyst versions before 5.71001 - in 5.71001
142 attributes work as expected, and the BUILD method is called normally
143 (although BUILDARGS is not).
145 If you depend on Catalyst 5.8, then B<all> Moose features work as expected.
147 You will also see this issue if you do the following:
149 package TestApp::Controller::Example;
151 use base 'Catalyst::Controller';
153 as C< use base > appends to @ISA.
155 =head3 use Moose in MyApp
157 Similar to the above, this will also fail:
166 If you need to use Moose in your application class (e.g. for method modifiers
167 etc.) then the correct technique is:
175 __PACKAGE__->config( name => 'MyApp' );
176 __PACKAGE__->setup(qw/
180 =head2 Anonymous closures installed directly into the symbol table
182 If you have any code which installs anonymous subroutine references directly
183 into the symbol table, you may encounter breakages. The simplest solution is
184 to use L<Sub::Name> to name the subroutine. Example:
186 # Original code, likely to break:
187 my $full_method_name = join('::', $package_name, $method_name);
188 *$full_method_name = sub { ... };
191 use Sub::Name 'subname';
192 my $full_method_name = join('::',$package_name, $method_name);
193 *$full_method_name = subname $full_method_name, sub { ... };
195 Additionally, you can take advantage of Catalyst's use of L<Class::MOP> and
196 install the closure using the appropriate metaclass. Example:
199 my $metaclass = Moose::Meta::Class->initialize($package_name);
200 $metaclass->add_method($method_name => sub { ... });
202 =head2 Hooking into application setup
204 To execute code during application start-up, the following snippet in MyApp.pm
208 my ($class, @args) = @_;
209 $class->NEXT::setup(@args);
210 ... # things to do after the actual setup
213 With Catalyst 5.80 this won't work anymore, because Catalyst no longer
214 uses NEXT.pm for method resolution. The functionality was only ever
215 originally operational as L<NEXT> remembers what methods have already
216 been called, and will not call them again.
218 Using this now causes infinite recursion between MyApp::setup and
219 Catalyst::setup, due to other backwards compatibility issues related to how
220 plugin setup works. Moose method modifiers like C<< before|after|around setup
221 => sub { ... }; >> also will not operate correctly on the setup method.
223 The right way to do it is this:
225 after setup_finalize => sub {
226 ... # things to do after the actual setup
229 The setup_finalize hook was introduced as a way to avoid this issue.
231 =head2 Components with a new method which returns false
233 Previously, if you had a component which inherited from Catalyst::COMPONENT,
234 but overrode the new method to return false, then your class's configuration
235 would be blessed into a hash on your behalf, and this would be returned from
236 the COMPONENT method.
238 This behavior makes no sense, and so has been removed. Implementing your own
239 C< new > method in components is B<highly> discouraged. Instead, you should
240 inherit the new method from Catalyst::Component, and use Moose's BUILD
241 functionality and/or Moose attributes to perform any construction work
242 necessary for your class.
244 =head2 __PACKAGE__->mk_accessor('meta');
246 Won't work due to a limitation of L<Moose>. This is currently being fixed
249 =head2 Class::Data::Inheritable side effects
251 Previously, writing to a class data accessor would copy the accessor method
252 down into your package.
254 This behavior has been removed. While the class data is still stored
255 per-class, it is stored on the metaclass of the class defining the accessor.
257 Therefore anything relying on the side effect of the accessor being copied down
260 The following test demonstrates the problem:
264 use base qw/Class::Data::Inheritable/;
265 __PACKAGE__->mk_classdata('foo');
270 use base qw/BaseClass/;
273 BaseClass->foo('base class');
274 Child->foo('sub class');
277 isnt(BaseClass->can('foo'), Child->can('foo'));
279 =head2 Extending Catalyst::Request or other classes in an ad-hoc manner using mk_accessors
281 Previously, it was possible to add additional accessors to Catalyst::Request
282 (or other classes) by calling the mk_accessors class method.
284 This is no longer supported - users should make a subclass of the class whose
285 behavior they would like to change, rather than globally polluting the
288 =head2 Confused multiple inheritance with Catalyst::Component::COMPONENT
290 Previously, Catalyst's COMPONENT method would delegate to the method on
291 the right hand side, which could then delegate back again with
292 NEXT. This is poor practice, and in addition, makes no sense with C3
293 method dispatch order, and is therefore no longer supported.
295 If a COMPONENT method is detected in the inheritance hierarchy to the right
296 hand side of Catalyst::Component::COMPONENT, then the following warning
297 message will be emitted:
299 There is a COMPONENT method resolving after Catalyst::Component
302 The correct fix is to re-arrange your class's inheritance hierarchy so that the
303 COMPONENT method you would like to inherit is the first (left-hand most)
304 COMPONENT method in your @ISA.
308 =head2 Actions in your application class
310 Having actions in your application class will now emit a warning at application
311 startup as this is deprecated. It is highly recommended that these actions are moved
312 into a MyApp::Controller::Root (as demonstrated by the scaffold application
313 generated by catalyst.pl).
315 This warning, also affects tests. You should move actions in your test,
316 creating a myTest::Controller::Root, like the following example:
318 package MyTest::Controller::Root;
323 use parent 'Catalyst::Controller';
325 __PACKAGE__->config(namespace => '');
328 my ( $self, $c ) = @_;
334 =head2 ::[MVC]:: naming scheme
336 Having packages called MyApp::[MVC]::XX is deprecated and can no longer be generated
339 This is still supported, but it is recommended that you rename your application
340 components to Model/View/Controller.
342 A warning will be issued at application startup if the ::[MVC]:: naming scheme is
345 =head2 Catalyst::Base
347 Any code using L<Catalyst::Base> will now emit a warning; this
348 module will be removed in a future release.
350 =head2 Methods in Catalyst::Dispatcher
352 The following methods in Catalyst::Dispatcher are implementation
353 details, which may change in the 5.8X release series, and therefore their use
354 is highly deprecated.
362 =item registered_dispatch_types
364 =item method_action_class
372 The first time one of these methods is called, a warning will be emitted:
374 Class $class is calling the deprecated method Catalyst::Dispatcher::$public_method_name,
375 this will be removed in Catalyst 5.9X
377 You should B<NEVER> be calling any of these methods from application code.
379 Plugin authors and maintainers whose plugins currently call these methods
380 should change to using the public API, or, if you do not feel the public API
381 adequately supports your use case, please email the development list to
382 discuss what API features you need so that you can be appropriately supported.
384 =head2 Class files with names that don't correspond to the packages they define
386 In this version of Catalyst, if a component is loaded from disk, but no
387 symbols are defined in that component's name space after it is loaded, this
388 warning will be issued:
390 require $class was successful but the package is not defined.
392 This is to protect against confusing bugs caused by mistyping package names,
393 and will become a fatal error in a future version.
395 Please note that 'inner packages' (via L<Devel::InnerPackage>) are still fully
396 supported; this warning is only issued when component file naming does not map
397 to B<any> of the packages defined within that component.
399 =head2 $c->plugin method
401 Calling the plugin method is deprecated, and calling it at run time is B<highly
404 Instead you are recommended to use L<Catalyst::Model::Adaptor> or similar to
405 compose the functionality you need outside of the main application name space.
407 Calling the plugin method will not be supported past Catalyst 5.81.