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 =head1 Known backwards compatibility breakages
39 =head2 Applications in a single file
41 Applications must be in their own file, and loaded at compile time. This
42 issue generally only affects the tests of CPAN distributions. Your
43 application will fail if you try to define an application inline in a
44 block, and use plugins which supply a C< new > method, then use that
45 application latter in tests within the same file.
47 This is due to the fact that Catalyst is inlining a new method on your
48 application class allowing it to be compatible with Moose. The method
49 used to do this changed in 5.80004 to avoid the possibility of reporting
50 an 'Unknown Error' if your application failed to compile.
52 =head2 Issues with Class::C3
54 Catalyst 5.80 uses the L<Algorithm::C3> method dispatch order. This is
55 built into Perl 5.10, and comes via L<Class::C3> for Perl 5.8. This
56 replaces L<NEXT> with L<Class::C3::Adopt::NEXT>, forcing all components
57 to resolve methods using C3, rather than the unpredictable dispatch
60 This issue is characterised by your application failing to start due to an
61 error message about having a non-linear @ISA.
63 The Catalyst plugin most often causing this is
64 L<Catalyst::Plugin::Session::Store::FastMmap> - if you are using this
65 plugin and see issues, then please upgrade your plugins, as it has been
66 fixed. Note that Makefile.PL in the distribution will warn about known
67 incompatible components.
69 This issue can, however, be found in your own application - the only solution is
70 to go through each base class of the class the error was reported against, until
71 you identify the ones in conflict, and resolve them.
73 To be able to generate a linear @ISA, the list of superclasses for each
74 class must be resolvable using the C3 algorithm. Unfortunately, when
75 superclasses are being used as mixins (to add functionality used in your class),
76 and with multiple inheritence, it is easy to get this wrong.
78 Most common is the case of:
80 package Component1; # Note, this is the common case
81 use base qw/Class::Accessor::Fast Class::Data::Inheritable/;
83 package Component2; # Accidentally saying it this way causes a failure
84 use base qw/Class::Data::Inheritable Class::Accessor::Fast/;
87 use base qw/Component1 Component2/;
89 Any situation like this will cause your application to fail to start.
91 For additional documentation about this issue, and how to resolve it, see
92 L<Class::C3::Adopt::NEXT>.
94 =head2 Components which inherit from Moose::Object before Catalyst::Component
96 Moose components which say:
98 package TestApp::Controller::Example;
100 extends qw/Moose::Object Catalyst::Component/;
102 to use the constructor provided by Moose, while working (if you do some hacks
103 with the C< BUILDARGS > method), will not work with Catalyst 5.80 as
104 C<Catalyst::Component> inherits from C<Moose::Object>, and so C< @ISA > fails
107 The fix for this is to not inherit directly from C<Moose::Object>
108 yourself. Having components which do not inherit their constructor from
109 C<Catalyst::Component> is B<unsupported>, and has never been recommended,
110 therefore you're on your own if you're using this technique. You'll need
111 to detect the version of Catalyst your application is running, and deal
112 with it appropriately.
114 You will also see this issue if you do the following:
116 package TestApp::Controller::Example;
118 use base 'Catalyst::Controller';
120 as C< use base > appends to @ISA.
122 The correct way to use Moose in a component in a both forward and backwards
125 package TestApp::Controller::Root;
127 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
129 Note that the C< extends > declaration needs to occur in a begin block for
130 L<attributes> to operate correctly.
132 You also don't get the L<Moose::Object> constructor, and therefore attribute
133 initialization will not work as normally expected. If you want to use Moose
134 attributes, then they need to be made lazy to correctly initialize.
136 Note that this only applies if your component needs to maintain component
137 backwards compatibility for Catalyst versions before 5.71001 - in 5.71001
138 attributes work as expected, and the BUILD method is called normally
139 (although BUILDARGS is not).
141 If you depend on Catalyst 5.8, then B<all> Moose features work as expected.
143 =head3 use Moose in MyApp
145 Similar to the above, this will also fail:
154 If you need to use Moose in your application class (e.g. for method modifiers
155 etc.) then the correct technique is:
163 __PACKAGE__->config( name => 'MyApp' );
164 __PACKAGE__->setup(qw/
168 =head2 Anonymous closures installed directly into the symbol table
170 If you have any code which installs anonymous subroutine references directly
171 into the symbol table, you may encounter breakages. The simplest solution is
172 to use L<Sub::Name> to name the subroutine. Example:
174 # Original code, likely to break:
175 my $full_method_name = join('::', $package_name, $method_name);
176 *$full_method_name = sub { ... };
179 use Sub::Name 'subname';
180 my $full_method_name = join('::',$package_name, $method_name);
181 *$full_method_name = subname $full_method_name, sub { ... };
183 Additionally, you can take advantage of Catalyst's use of L<Class::MOP> and
184 install the closure using the appropriate metaclass. Example:
187 my $metaclass = Moose::Meta::Class->initialize($package_name);
188 $metaclass->add_method($method_name => sub { ... });
190 =head2 Hooking into application setup
192 To execute code during application start-up, the following snippet in MyApp.pm
196 my ($class, @args) = @_;
197 $class->NEXT::setup(@args);
198 ... # things to do after the actual setup
201 With Catalyst 5.80 this won't work anymore, because Catalyst no longer
202 uses NEXT.pm for method resolution. The functionality was only ever
203 originally operational as L<NEXT> remembers what methods have already
204 been called, and will not call them again.
206 Using this now causes infinite recursion between MyApp::setup and
207 Catalyst::setup, due to other backwards compatibility issues related to how
208 plugin setup works. Moose method modifiers like C<< before|after|around 'setup
209 => sub { ... }; >> also will not operate correctly on the setup method.
211 The right way to do it is this:
213 after setup_finalize => sub {
214 ... # things to do after the actual setup
217 The setup_finalize hook was introduced as a way to avoid this issue.
219 =head2 Components with a new method which returns false
221 Previously, if you had a component which inherited from Catalyst::COMPONENT,
222 but overrode the new method to return false, then your class's configuration
223 would be blessed into a hash on your behalf, and this would be returned from
224 the COMPONENT method.
226 This behavior makes no sense, and so has been removed. Implementing your own
227 C< new > method in components is B<highly> discouraged. Instead, you should
228 inherit the new method from Catalyst::Component, and use Moose's BUILD
229 functionality and/or Moose attributes to perform any construction work
230 necessary for your class.
232 =head2 __PACKAGE__->mk_accessor('meta');
234 Won't work due to a limitation of L<Moose>. This is currently being fixed
237 =head2 Class::Data::Inheritable side effects
239 Previously, writing to a class data accessor would copy the accessor method
240 down into your package.
242 This behavior has been removed. While the class data is still stored
243 per-class, it is stored on the metaclass of the class defining the accessor.
245 Therefore anything relying on the side effect of the accessor being copied down
248 The following test demonstrates the problem:
252 use base qw/Class::Data::Inheritable/;
253 __PACKAGE__->mk_classdata('foo');
258 use base qw/BaseClass/;
261 BaseClass->foo('base class');
262 Child->foo('sub class');
265 isnt(BaseClass->can('foo'), Child->can('foo'));
267 =head2 Extending Catalyst::Request or other classes in an ad-hoc manner using mk_accessors
269 Previously, it was possible to add additional accessors to Catalyst::Request
270 (or other classes) by calling the mk_accessors class method.
272 This is no longer supported - users should make a subclass of the class whose
273 behavior they would like to change, rather than globally polluting the
276 =head2 Confused multiple inheritance with Catalyst::Component::COMPONENT
278 Previously, Catalyst's COMPONENT method would delegate to the method on
279 the right hand side, which could then delegate back again with
280 NEXT. This is poor practice, and in addition, makes no sense with C3
281 method dispatch order, and is therefore no longer supported.
283 If a COMPONENT method is detected in the inheritance hierarchy to the right
284 hand side of Catalyst::Component::COMPONENT, then the following warning
285 message will be emitted:
287 There is a COMPONENT method resolving after Catalyst::Component
290 The correct fix is to re-arrange your class's inheritance hierarchy so that the
291 COMPONENT method you would like to inherit is the first (left-hand most)
292 COMPONENT method in your @ISA.
296 =head2 Catalyst::Base
298 Any code using L<Catalyst::Base> will now emit a warning; this
299 module will be removed in a future release.
301 =head2 Methods in Catalyst::Dispatcher
303 The following methods in Catalyst::Dispatcher are implementation
304 details, which may change in the 5.8X release series, and therefore their use
305 is highly deprecated.
313 =item registered_dispatch_types
315 =item method_action_class
323 The first time one of these methods is called, a warning will be emitted:
325 Class $class is calling the deprecated method Catalyst::Dispatcher::$public_method_name,
326 this will be removed in Catalyst 5.9X
328 You should B<NEVER> be calling any of these methods from application code.
330 Plugin authors and maintainers whose plugins currently call these methods
331 should change to using the public API, or, if you do not feel the public API
332 adequately supports your use case, please email the development list to
333 discuss what API features you need so that you can be appropriately supported.
335 =head2 Class files with names that don't correspond to the packages they define
337 In this version of Catalyst, if a component is loaded from disk, but no
338 symbols are defined in that component's name space after it is loaded, this
339 warning will be issued:
341 require $class was successful but the package is not defined.
343 This is to protect against confusing bugs caused by mistyping package names,
344 and will become a fatal error in a future version.
346 Please note that 'inner packages' (via L<Devel::InnerPackage>) are still fully
347 supported; this warning is only issued when component file naming does not map
348 to B<any> of the packages defined within that component.
350 =head2 $c->plugin method
352 Calling the plugin method is deprecated, and calling it at run time is B<highly
355 Instead you are recommended to use L< Catalyst::Model::Adaptor > or similar to
356 compose the functionality you need outside of the main application name space.
358 Calling the plugin method will not be supported past Catalyst 5.81.