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 Declaring actions in Roles is currently unsupported.
37 =head2 Using Moose in Components
39 The correct way to use Moose in a component in a both forward and backwards
42 package TestApp::Controller::Root;
44 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
46 See L<Components which inherit from Moose::Object before Catalyst::Component>.
48 =head1 Known backwards compatibility breakages
50 =head2 Applications in a single file
52 Applications must be in their own file, and loaded at compile time. This
53 issue generally only affects the tests of CPAN distributions. Your
54 application will fail if you try to define an application inline in a
55 block, and use plugins which supply a C< new > method, then use that
56 application latter in tests within the same file.
58 This is due to the fact that Catalyst is inlining a new method on your
59 application class allowing it to be compatible with Moose. The method
60 used to do this changed in 5.80004 to avoid the possibility of reporting
61 an 'Unknown Error' if your application failed to compile.
63 =head2 Issues with Class::C3
65 Catalyst 5.80 uses the L<Algorithm::C3> method dispatch order. This is
66 built into Perl 5.10, and comes via L<Class::C3> for Perl 5.8. This
67 replaces L<NEXT> with L<Class::C3::Adopt::NEXT>, forcing all components
68 to resolve methods using C3, rather than the unpredictable dispatch
71 This issue is characterised by your application failing to start due to an
72 error message about having a non-linear @ISA.
74 The Catalyst plugin most often causing this is
75 L<Catalyst::Plugin::Session::Store::FastMmap> - if you are using this
76 plugin and see issues, then please upgrade your plugins, as it has been
77 fixed. Note that Makefile.PL in the distribution will warn about known
78 incompatible components.
80 This issue can, however, be found in your own application - the only solution is
81 to go through each base class of the class the error was reported against, until
82 you identify the ones in conflict, and resolve them.
84 To be able to generate a linear @ISA, the list of superclasses for each
85 class must be resolvable using the C3 algorithm. Unfortunately, when
86 superclasses are being used as mixins (to add functionality used in your class),
87 and with multiple inheritence, it is easy to get this wrong.
89 Most common is the case of:
91 package Component1; # Note, this is the common case
92 use base qw/Class::Accessor::Fast Class::Data::Inheritable/;
94 package Component2; # Accidentally saying it this way causes a failure
95 use base qw/Class::Data::Inheritable Class::Accessor::Fast/;
98 use base qw/Component1 Component2/;
100 Any situation like this will cause your application to fail to start.
102 For additional documentation about this issue, and how to resolve it, see
103 L<Class::C3::Adopt::NEXT>.
105 =head2 Components which inherit from Moose::Object before Catalyst::Component
107 Moose components which say:
109 package TestApp::Controller::Example;
111 extends qw/Moose::Object Catalyst::Component/;
113 to use the constructor provided by Moose, while working (if you do some hacks
114 with the C< BUILDARGS > method), will not work with Catalyst 5.80 as
115 C<Catalyst::Component> inherits from C<Moose::Object>, and so C< @ISA > fails
118 The correct way to use Moose in a component in a both forward and backwards
121 package TestApp::Controller::Root;
123 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
125 Note that the C< extends > declaration needs to occur in a begin block for
126 L<attributes> to operate correctly.
128 This way you do not inherit directly from C<Moose::Object>
129 yourself. Having components which do not inherit their constructor from
130 C<Catalyst::Component> is B<unsupported>, and has never been recommended,
131 therefore you're on your own if you're using this technique. You'll need
132 to detect the version of Catalyst your application is running, and deal
133 with it appropriately.
135 You also don't get the L<Moose::Object> constructor, and therefore attribute
136 initialization will not work as normally expected. If you want to use Moose
137 attributes, then they need to be made lazy to correctly initialize.
139 Note that this only applies if your component needs to maintain component
140 backwards compatibility for Catalyst versions before 5.71001 - in 5.71001
141 attributes work as expected, and the BUILD method is called normally
142 (although BUILDARGS is not).
144 If you depend on Catalyst 5.8, then B<all> Moose features work as expected.
146 You will also see this issue if you do the following:
148 package TestApp::Controller::Example;
150 use base 'Catalyst::Controller';
152 as C< use base > appends to @ISA.
154 =head3 use Moose in MyApp
156 Similar to the above, this will also fail:
165 If you need to use Moose in your application class (e.g. for method modifiers
166 etc.) then the correct technique is:
174 __PACKAGE__->config( name => 'MyApp' );
175 __PACKAGE__->setup(qw/
179 =head2 Anonymous closures installed directly into the symbol table
181 If you have any code which installs anonymous subroutine references directly
182 into the symbol table, you may encounter breakages. The simplest solution is
183 to use L<Sub::Name> to name the subroutine. Example:
185 # Original code, likely to break:
186 my $full_method_name = join('::', $package_name, $method_name);
187 *$full_method_name = sub { ... };
190 use Sub::Name 'subname';
191 my $full_method_name = join('::',$package_name, $method_name);
192 *$full_method_name = subname $full_method_name, sub { ... };
194 Additionally, you can take advantage of Catalyst's use of L<Class::MOP> and
195 install the closure using the appropriate metaclass. Example:
198 my $metaclass = Moose::Meta::Class->initialize($package_name);
199 $metaclass->add_method($method_name => sub { ... });
201 =head2 Hooking into application setup
203 To execute code during application start-up, the following snippet in MyApp.pm
207 my ($class, @args) = @_;
208 $class->NEXT::setup(@args);
209 ... # things to do after the actual setup
212 With Catalyst 5.80 this won't work anymore, because Catalyst no longer
213 uses NEXT.pm for method resolution. The functionality was only ever
214 originally operational as L<NEXT> remembers what methods have already
215 been called, and will not call them again.
217 Using this now causes infinite recursion between MyApp::setup and
218 Catalyst::setup, due to other backwards compatibility issues related to how
219 plugin setup works. Moose method modifiers like C<< before|after|around 'setup
220 => sub { ... }; >> also will not operate correctly on the setup method.
222 The right way to do it is this:
224 after setup_finalize => sub {
225 ... # things to do after the actual setup
228 The setup_finalize hook was introduced as a way to avoid this issue.
230 =head2 Components with a new method which returns false
232 Previously, if you had a component which inherited from Catalyst::COMPONENT,
233 but overrode the new method to return false, then your class's configuration
234 would be blessed into a hash on your behalf, and this would be returned from
235 the COMPONENT method.
237 This behavior makes no sense, and so has been removed. Implementing your own
238 C< new > method in components is B<highly> discouraged. Instead, you should
239 inherit the new method from Catalyst::Component, and use Moose's BUILD
240 functionality and/or Moose attributes to perform any construction work
241 necessary for your class.
243 =head2 __PACKAGE__->mk_accessor('meta');
245 Won't work due to a limitation of L<Moose>. This is currently being fixed
248 =head2 Class::Data::Inheritable side effects
250 Previously, writing to a class data accessor would copy the accessor method
251 down into your package.
253 This behavior has been removed. While the class data is still stored
254 per-class, it is stored on the metaclass of the class defining the accessor.
256 Therefore anything relying on the side effect of the accessor being copied down
259 The following test demonstrates the problem:
263 use base qw/Class::Data::Inheritable/;
264 __PACKAGE__->mk_classdata('foo');
269 use base qw/BaseClass/;
272 BaseClass->foo('base class');
273 Child->foo('sub class');
276 isnt(BaseClass->can('foo'), Child->can('foo'));
278 =head2 Extending Catalyst::Request or other classes in an ad-hoc manner using mk_accessors
280 Previously, it was possible to add additional accessors to Catalyst::Request
281 (or other classes) by calling the mk_accessors class method.
283 This is no longer supported - users should make a subclass of the class whose
284 behavior they would like to change, rather than globally polluting the
287 =head2 Confused multiple inheritance with Catalyst::Component::COMPONENT
289 Previously, Catalyst's COMPONENT method would delegate to the method on
290 the right hand side, which could then delegate back again with
291 NEXT. This is poor practice, and in addition, makes no sense with C3
292 method dispatch order, and is therefore no longer supported.
294 If a COMPONENT method is detected in the inheritance hierarchy to the right
295 hand side of Catalyst::Component::COMPONENT, then the following warning
296 message will be emitted:
298 There is a COMPONENT method resolving after Catalyst::Component
301 The correct fix is to re-arrange your class's inheritance hierarchy so that the
302 COMPONENT method you would like to inherit is the first (left-hand most)
303 COMPONENT method in your @ISA.
307 =head2 Actions in your application class
309 Having actions in your application class will now emit a warning at application
310 startup as this is deprecated. It is highly recommended that these actions are moved
311 into a MyApp::Controller::Root (as demonstrated by the scaffold application
312 generated by catalyst.pl)
314 =head2 ::[MVC]:: naming scheme
316 Having packages called MyApp::[MVC]::XX is deprecated and can no longer be generated
319 This is still supported, but it is recommended that you rename your application
320 components to Model/View/Controller.
322 A warning will be issued at application startup if the ::[MVC]:: naming scheme is
325 =head2 Catalyst::Base
327 Any code using L<Catalyst::Base> will now emit a warning; this
328 module will be removed in a future release.
330 =head2 Methods in Catalyst::Dispatcher
332 The following methods in Catalyst::Dispatcher are implementation
333 details, which may change in the 5.8X release series, and therefore their use
334 is highly deprecated.
342 =item registered_dispatch_types
344 =item method_action_class
352 The first time one of these methods is called, a warning will be emitted:
354 Class $class is calling the deprecated method Catalyst::Dispatcher::$public_method_name,
355 this will be removed in Catalyst 5.9X
357 You should B<NEVER> be calling any of these methods from application code.
359 Plugin authors and maintainers whose plugins currently call these methods
360 should change to using the public API, or, if you do not feel the public API
361 adequately supports your use case, please email the development list to
362 discuss what API features you need so that you can be appropriately supported.
364 =head2 Class files with names that don't correspond to the packages they define
366 In this version of Catalyst, if a component is loaded from disk, but no
367 symbols are defined in that component's name space after it is loaded, this
368 warning will be issued:
370 require $class was successful but the package is not defined.
372 This is to protect against confusing bugs caused by mistyping package names,
373 and will become a fatal error in a future version.
375 Please note that 'inner packages' (via L<Devel::InnerPackage>) are still fully
376 supported; this warning is only issued when component file naming does not map
377 to B<any> of the packages defined within that component.
379 =head2 $c->plugin method
381 Calling the plugin method is deprecated, and calling it at run time is B<highly
384 Instead you are recommended to use L< Catalyst::Model::Adaptor > or similar to
385 compose the functionality you need outside of the main application name space.
387 Calling the plugin method will not be supported past Catalyst 5.81.