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 as 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 solve, and a
15 complete description of behaviour changes which may cause compatibility issues,
16 or warnings which are now emitted is included below to help if you have problems.
18 If you think you have found an upgrade related issue which is not covered in
19 this document, then please email the Catalyst list to discuss the problem.
23 =head2 Application class roles.
25 You can only apply method modifiers after the applications C<< ->setup >>
26 method has been called. This means that modifiers will not work with methods
27 which run during the call to C<< ->setup >>.
29 =head2 Controller actions in Moose roles
33 =head1 Known backwards compatibility breakages.
35 =head2 Applications in a single file.
37 Applications must be in their own file, and loaded at compile time. This
38 issue generally only affects the tests of cpan distributions. Defining an
39 application inline in a block, and using plugins which supply a C< new >
40 method, then using that application latter in tests, within the same file
41 will cause your application to fail.
43 This is due to the fact that Catalyst is inlining a new method on your
44 application class allowing it to be compatible with Moose. The method used
45 to do this changed in 5.80004 to avoid the possibility of reporting
46 'Unknown Error' if your application failed to compile.
48 =head2 Issues with Class::C3
50 Catalyst 5.80 uses L<Algorithm::C3> method dispatch order. This is built into
51 perl 5.10, and comes via L<Class::C3> for perl 5.8. This replaces L<NEXT>
52 with L<Class::C3::Adopt::NEXT>, forcing all components to resolve methods using
53 C3, rather than the unpredictable dispatch order of L<NEXT>.
55 This issue is characterised by your application failing to start due to an
56 error message about having a non-linear @ISA.
58 The Catalyst plugin most often causing this, is
59 L<Catalyst::Plugin::Session::Store::FastMmap> - if you are using this plugin
60 and see issues, then please upgrade - and please try upgrading your plugins
61 if you have this issue, as it has been fixed. Note that Makefile.PL in the
62 distribution will warn about known incompatible components.
64 This issue can, however, be found in your own application - the only solution is
65 to go through each base class of the class the error was reported against, until
66 you identify the ones in conflict, and resolve them.
68 To be able to generate a linear @ISA, the list of superclasses for each
69 class must be resolvable using the C3 algorithm. Unfortunately, when
70 superclasses are being used as mixins (to add functionality used in your class),
71 and with multiple inheritence, it is easy to get this wrong.
73 Most common is the case of:
75 package Component1; # Note, this is the common case
76 use base qw/Class::Accessor::Fast Class::Data::Inheritable/;
78 package Component2; # Accidentally saying it this way round causes fail.
79 use base qw/Class::Data::Inheritable Class::Accessor::Fast/;
82 use base qw/Component1 Component2/;
84 Any situation like this will cause your application to fail to start.
86 Please see additional documentation about this issue, and how to resolve it in
87 L<Class::C3::Adopt::NEXT>.
89 =head2 Components which inherit from Moose::Object before Catalyst::Component
91 Moose components which say:
93 package TestApp::Controller::Example;
95 extends qw/Moose::Object Catalyst::Component/;
97 to use the constructor provided by Moose, whilst working (if you do some hacks
98 with the C< BUILDARGS > method), will not work with Catalyst 5.80 as
99 C<Catalyst::Component> inherits from C<Moose::Object>, and so C< @ISA > fails
102 The fix for this is to not inherit directly from C<Moose::Object>
103 yourself. Having components which do not inherit their constructor from
104 C<Catalyst::Component> is B<unsupported>, and has never been recommended,
105 therefore you're on your own if you're using this technique. You'll need
106 to detect the version of Catalyst your application is running with and deal
107 with it appropriately.
109 You will also see this issue if you do the following:
111 package TestApp::Controller::Example;
113 use base 'Catalyst::Controller';
115 as C< use base > appends to @ISA.
117 The correct way to use Moose in a component in a both forward and backwards
120 package TestApp::Controller::Root;
122 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
124 Note that the C< extends > declaration needs to occur in a begin block for
125 L<attributes> to operate correctly.
127 You also don't get the L<Moose::Object> constructor, and therefore attribute
128 initialization will not work as normally expected. If you want to use Moose
129 attributes, then they need to be made lazy to correctly initialize.
131 Note that this only applies if your component needs to maintain component
132 backwards compatibility for Catalyst versions before 5.71001 - in 5.71001
133 attributes work as expected, and the BUILD method is called normally
134 (although BUILDARGS is not).
136 If you depend on Catalyst 5.8, then B<all> Moose features work as expected.
138 =head3 use Moose in MyApp
140 Similar to the above, this will also fail:
149 If you need to use Moose in your application class (e.g. for method modifiers
150 etc) then the correct technique is:
158 __PACKAGE__->config( name => 'MyApp' );
159 __PACKAGE__->setup(qw/
163 =head2 Anonymous closures installed directly into the symbol table
165 If you have any code which installs anonymous subroutine references directly
166 into the symbol table, you may encounter breakages. The simplest solution is
167 to use L<Sub::Name> to name the subroutine. Example:
169 # Original code, likely to break:
170 my $full_method_name = join('::', $package_name, $method_name);
171 *$full_method_name = sub { ... };
174 use Sub::Name 'subname';
175 my $full_method_name = join('::',$package_name, $method_name);
176 *$full_method_name = subname $full_method_name, sub { ... };
178 Additionally, you can take advantage of Catalysts use of L<Class::MOP> and
179 install the closure using the appropriate meta class. Example:
182 my $metaclass = Moose::Meta::Class->initialize($package_name);
183 $metaclass->add_method($method_name => sub { ... });
185 =head2 Hooking into application setup
187 To execute code during application start-up the following snippet in MyApp.pm
191 my ($class, @args) = @_;
192 $class->NEXT::setup(@args);
193 ... # things to do after the actual setup
196 With Catalyst 5.80 this won't work anymore. Due to the fact that Catalyst is
197 no longer using NEXT.pm for method resolution, this no longer works. The
198 functionality was only ever originally operational as L<NEXT> remembers what
199 methods have already been called, and will not call them again.
201 Using this now causes infinite recursion between MyApp::setup and
202 Catalyst::setup, due to other backwards compatibility issues related to how
203 plugin setup works. Moose method modifiers like C<< before|after|around 'setup
204 => sub { ... }; >> also will not operate correctly on the setup method.
206 The right way to do it is this:
208 after setup_finalize => sub {
209 ... # things to do after the actual setup
212 The setup_finalize hook was introduced as a way to avoid this issue.
214 =head2 Components with a new method which returns false
216 Previously, if you had a component which inherited from Catalyst::COMPONENT,
217 but overrode the new method to return false, then your class' configuration
218 would be blessed into a hash on your behalf, and this would be returned from
219 the COMPONENT method.
221 This behaviour makes no sense, and so has been removed. Implementing your own
222 C< new > method in components is B<highly> discouraged, instead, you should
223 inherit the new method from Catalyst::Component, and use Mooses BUILD
224 functionality and/or Moose attributes to perform any construction work
225 necessary for your class.
227 =head2 __PACKAGE__->mk_accessor('meta');
229 Won't work due to a limitation of L<Moose>. This is currently being fixed
232 =head2 Class::Data::Inheritable side effects
234 Previously, writing to a class data accessor would copy the accessor method
235 down into your package.
237 This behaviour has been removed. Whilst the class data is still stored
238 per-class, it is stored on the metaclass of the class defining the accessor.
240 Therefore anything relying on the side-effect of the accessor being copied down
243 The following test demonstrates the problem:
247 use base qw/Class::Data::Inheritable/;
248 __PACKAGE__->mk_classdata('foo');
253 use base qw/BaseClass/;
256 BaseClass->foo('base class');
257 Child->foo('sub class');
260 isnt(BaseClass->can('foo'), Child->can('foo'));
262 =head2 Extending Catalyst::Request or other classes in an ad-hoc manor using mk_accessors
264 Previously, it was possible to add additional accessors to Catalyst::Request
265 (or other classes) by calling the mk_accessors class method.
267 This is no longer supported - users should make a sub-class of the class whose
268 behaviour they would like to change, rather than globally polluting the
271 =head2 Confused multiple inheritance with Catalyst::Component::COMPONENT
273 Previously, Catalyst's COMPONENT method would delegate to the method on the
274 right hand side, which could then delegate back again with NEXT. This (as it
275 is insane AND makes no sense with C3 method dispatch order), and is therefore
278 If a COMPONENT method is detected in the inheritance hierarchy to the right
279 hand side of Catalyst::Component::COMPONENT, then the following warning
280 message will be emitted:
282 There is a COMPONENT method resolving after Catalyst::Component
285 The correct fix is to re-arrange your class' inheritance hierarchy so that the
286 COMPONENT method you would like to inherit is the first (left-hand most)
287 COMPONENT method in your @ISA.
291 =head2 Catalyst::Base
293 Any code using L<Catalyst::Base> will now warn, and this module will be removed
296 =head2 Methods in Catalyst::Dispatcher
298 The following methods in Catalyst::Dispatcher are both an implementation
299 detail, which may change in the 5.8X release series, and therefore their use
300 is highly deprecated.
308 =item registered_dispatch_types
310 =item method_action_class
318 The first time one of these methods is called, a warning will be emitted:
320 Class $class is calling the deprecated method Catalyst::Dispatcher::$public_method_name,
321 this will be removed in Catalyst 5.9X
323 You should B<NEVER> be calling any of these methods from application code.
325 Plugins authors and maintainers whose plugins currently call these methods
326 should change to using the public API, or, if you do not feel the public API
327 adequately supports your use-case, please email the development list to
328 discuss what API features you need so that you can be appropriately supported.
330 =head2 Class files with names that don't correspond to the packages they define
332 In this version of Catalyst, if a component is loaded from disk, but no
333 symbols are defined in that component's name space after it is loaded, this
334 warning will be issued:
336 require $class was successful but the package is not defined.
338 This is to protect against confusing bugs caused by mis-typing package names,
339 and will become a fatal error in a future version.
341 Please note that 'inner packages' (via L<Devel::InnerPackage>) are still fully
342 supported, this warning is only issued when component file naming does not map
343 to B<any> of the packages defined within that component.
345 =head2 $c->plugin method
347 Calling the plugin method is deprecated, and calling it at run time is B<highly
350 Instead you are recommended to use L< Catalyst::Model::Adaptor > or similar to
351 compose the functionality you need outside of the main application name space.
353 Calling the plugin method will not be supported past Catalyst 5.81.