1 =head1 Upgrading to Catalyst 5.80
3 Most applications and plugins should run unaltered on Catalyst 5.80.
5 However as a lot of refactoring work has taken place, and several changes have
6 been made which could cause incompatibilities. If your application or plugin
7 is using deprecated code, or relying on side-effects, then you could have
8 issues upgrading to this release.
10 Most issues found with pre-existing components have been easy to solve, and a
11 complete description of behaviour changes which may cause compatibility issues,
12 or warnings which are now emitted is included below to help if you have problems.
14 If you think you have found an upgrade related issue which is not covered in
15 this document, then please email the Catalyst list to discuss the problem.
17 =head1 Known backwards compatibility breakages.
19 =head2 Issues with Class::C3
21 Catalyst 5.80 uses L<Algorithm::C3> method dispatch order. This is built into
22 perl 5.10, and comes via L<Class::C3> for perl 5.8. This replaces L<NEXT>
23 with L<Class::C3::Adopt::NEXT>, forcing all components to resolve methods using
24 C3, rather than the unpredictable dispatch order of L<NEXT>.
26 To be able to do this, however, entails that the graph of superclasses for each
27 class must be linearizable using the C3 algorithm. Unfortunately, when
28 superclasses are being used as mixins, it is easy to get this wrong.
30 Most common is the case of:
32 package Component1; # Note, this is the common case
33 use base qw/Class::Accessor::Fast Class::Data::Inheritable/;
35 package Component2; # Accidentally saying it this way round causes fail.
36 use base qw/Class::Data::Inheritable Class::Accessor::Fast/;
39 use base qw/Component1 Component2/;
41 And the Catalyst plugin most often causing this, is
42 L<Catalyst::Plugin::Sesssion::Store::FastMMap> - if you are using this plugin
43 and see issues, then please upgrade!
45 This can, however, be found in your own application - the only solution is to
46 go through each base class of the class the error was reported against, until
47 you identify the ones in conflict, and resolve them.
49 =head2 Components which inherit from Moose::Object before Catalyst::Component
51 Moose components which say:
53 package TestApp::Controller::Example;
55 extends qw/Moose::Object Catalyst::Component/;
57 to use the constructor provided by Moose, whilst working (if you do some hacks
58 with the C< BUILDARGS > method), will not work with Catalyst 5.80 as
59 C<Catalyst::Component> inherits from C<Moose::Object>, and so C< @ISA > fails
62 The fix for this is to not inherit directly from C<Moose::Object>
63 yourself. Having components which do not inherit their constructor from
64 C<Catalyst::Component> is B<unsupported>, and has never been recommended,
65 therefore you're on your own if you're using this technique. You'll need
66 to detect the version of Catalyst your application is running with and deal
67 with it appropriately.
69 You will also see this issue if you do the following:
71 package TestApp::Controller::Example;
73 use base 'Catalyst::Controller';
75 as C< use base > appends to @ISA.
77 The correct way to use Moose in a component in a both forward and backwards
80 package TestApp::Controller::Root;
82 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
84 Note that the C< extends > declaration needs to occur in a begin block for
85 L<attributes> to operate correctly. You also don't get the L<Moose::Object>
86 constructor, and therefore attribute initialization will not work as normally
87 expected. If you want to use Moose attributes, then they need to be made lazy
88 to correctly initialize.
90 =head3 use Moose in MyApp
92 Similar to the above, this will also fail:
101 If you need to use Moose in your application class (e.g. for method modifiers
102 etc) then the correct technique is:
107 __PACKAGE__->setup(qw/
111 =head2 Anonymous closures installed directly into the symbol table
113 If you have any code which installs anonymous subroutine references directly
114 into the symbol table, you may encounter breakages. The simplest solution is
115 to use L<Sub::Name> to name the subroutine. Example:
117 # Original code, likely to break:
118 my $full_method_name = join('::', $package_name, $method_name);
119 *$full_method_name = sub { ... };
122 use Sub::Name 'subname';
123 my $full_method_name = join('::',$package_name, $method_name);
124 *$full_method_name = subname $full_method_name, sub { ... };
126 Additionally, you can take advantage of Catalysts use of L<Class::MOP> and
127 install the closure using the appropriate metaclass. Example:
130 my $metaclass = Moose::Meta::Class->initialize($package_name);
131 $metaclass->add_method($method_name => sub { ... });
133 =head2 Hooking into application setup
135 To execute code during application startup the following snippet in MyApp.pm
139 my ($class, @args) = @_;
140 $class->NEXT::setup(@args);
141 ... # things to do after the actual setup
144 With Catalyst 5.80 this won't work anymore. Due to the fact that Catalyst is
145 no longer using NEXT.pm for method resolution, this no longer works. The
146 functionality was only ever originally operational as L<NEXT> remembers what
147 methods have already been called, and will not call them again.
149 Using this now causes infinite recursion between MyApp::setup and
150 Catalyst::setup, due to other backwards compatibility issues related to how
151 plugin setup works. Moose method modifiers like C<< before|after|around 'setup
152 => sub { ... }; >> also will not operate correctly on the setup method.
154 The right way to do it is this:
156 after setup_finalize => sub {
157 ... # things to do after the actual setup
160 The setup_finalize hook was introduced as a way to void this issue.
162 =head2 Components with a new method which returns false
164 Previously, if you had a component which inherited from Catalyst::COMPONENT,
165 but overrode the new method to return false, then your class' configuration
166 would be blessed into a hash on your behalf, and this would be returned from
167 the COMPONENT method.
169 This behaviour makes no sense, and so has been removed. Implementing your own
170 C< new > method in components is B<highly> discouraged, instead, you should
171 inherit the new method from Catalyst::Component, and use Mooses BUILD
172 functionality and/or Moose attributes to perform any construction work
173 necessary for your class.
175 =head2 __PACKAGE__->mk_accessor('meta');
177 Won't work due to a limitation of L<Moose>. This is currently being fixed
180 =head2 Class::Data::Inheritable side effects
182 Previously, writing to a class data accessor would copy the accessor method
183 down into your package.
185 This behaviour has been removed. Whilst the class data is still stored
186 per-class, it is stored on the metaclass of the class defining the accessor.
188 Therefore anything relying on the side-effect of the accessor being copied down
191 The following test demonstrates the problem:
195 use base qw/Class::Data::Inheritable/;
196 __PACKAGE__->mk_classdata('foo');
201 use base qw/BaseClass/;
204 BaseClass->foo('base class');
205 Child->foo('sub class');
208 isnt(BaseClass->can('foo'), Child->can('foo'));
210 =head2 Extending Catalyst::Request or other classes in an ad-hoc manor using mk_accessors
212 Previously, it was possible to add additional accessors to Catalyst::Request
213 (or other classes) by calling the mk_accessors class method.
215 This is no longer supported - users should make a sub-class of the class whose
216 behaviour they would like to change, rather than globally polluting the
219 =head2 Confused multiple inheritance with Catalyst::Component::COMPONENT
221 Previously, Catalyst's COMPONENT method would delegate to the method on the
222 right hand side, which could then delegate back again with NEXT. This (as it
223 is insane AND makes no sense with C3 method dispatch order), and is therefore
226 If a COMPONENT method is detected in the inheritance hierarchy to the right
227 hand side of Catalyst::Component::COMPONENT, then the following warning
228 message will be emitted:
230 There is a COMPONENT method resolving after Catalyst::Component
233 The correct fix is to re-arrange your class' inheritance hierarchy so that the
234 COMPONENT method you would like to inherit is the first (left-hand most)
235 COMPONENT method in your @ISA.
239 =head2 Methods in Catalyst::Dispatcher
241 The following methods in Catalyst::Dispatcher are both an implementation
242 detail, which may change in the 5.8X release series, and therefore their use
243 is highly deprecated.
251 =item registered_dispatch_types
253 =item method_action_class
261 The first time one of these methods is called, a warning will be emitted:
263 Class $class is calling the deprecated method Catalyst::Dispatcher::$public_method_name,
264 this will be removed in Catalyst 5.9X
266 You should B<NEVER> be calling any of these methods from application code.
268 Plugins authors and maintainers whose plugins currently call these methods
269 should change to using the public API, or, if you do not feel the public API
270 adequately supports your use-case, please email the development list to
271 discuss what API features you need so that you can be appropriately supported.
273 =head2 Class naming to packages defined does not correspond.
275 In this version of Catalyst, if a component is loaded from disk, but no
276 symbols are defined in that component's name space after it is loaded, this
277 warning will be issued:
279 require $class was successful but the package is not defined.
281 This is to protect against confusing bugs caused by mis-typing package names,
282 and will become a fatal error in a future version.
284 Please note that 'inner packages' (via L<Devel::InnerPackage>) are still fully
285 supported, this warning is only issued when component file naming does not map
286 to B<any> of the packages defined within that component.
288 =head2 $c->plugin method
290 Calling the plugin method is deprecated, and calling it at runtime is B<highly
293 Instead you are recommended to use L< Catalyst::Model::Adaptor > or similar to
294 compose the functionality you need outside of the main application name space.
296 Calling the plugin method will not be supported past Catalyst 5.81.