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1 | =head1 NAME |
2 | |
3 | Catalyst::Upgrading - Instructions for upgrading to the latest Catalyst |
4 | |
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5 | =head1 Upgrading to Catalyst 5.80 |
6 | |
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7 | Most applications and plugins should run unaltered on Catalyst 5.80. |
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8 | |
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9 | However, a lot of refactoring work has taken place, and several changes have |
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10 | been made which could cause incompatibilities. If your application or plugin |
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11 | is using deprecated code, or relying on side effects, then you could have |
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12 | issues upgrading to this release. |
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13 | |
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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 |
17 | be unclear. |
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18 | |
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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. |
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21 | |
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22 | =head1 Moose features |
23 | |
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24 | =head2 Application class roles |
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25 | |
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26 | You can only apply method modifiers after the application's C<< ->setup >> |
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27 | method has been called. This means that modifiers will not work with methods |
28 | which run during the call to C<< ->setup >>. |
29 | |
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30 | See L<Catalyst::Manual::ExtendingCatalyst> for more information about using |
31 | L<Moose> in your applications. |
32 | |
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33 | =head2 Controller actions in Moose roles |
34 | |
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35 | Declaring actions in Roles is currently unsupported. |
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36 | |
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37 | =head1 Known backwards compatibility breakages |
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38 | |
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39 | =head2 Applications in a single file |
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40 | |
41 | Applications must be in their own file, and loaded at compile time. This |
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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. |
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46 | |
47 | This is due to the fact that Catalyst is inlining a new method on your |
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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. |
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51 | |
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52 | =head2 Issues with Class::C3 |
53 | |
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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 |
58 | order of L<NEXT>. |
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59 | |
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60 | This issue is characterised by your application failing to start due to an |
61 | error message about having a non-linear @ISA. |
62 | |
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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. |
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68 | |
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. |
72 | |
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. |
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77 | |
78 | Most common is the case of: |
79 | |
80 | package Component1; # Note, this is the common case |
81 | use base qw/Class::Accessor::Fast Class::Data::Inheritable/; |
82 | |
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83 | package Component2; # Accidentally saying it this way causes a failure |
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84 | use base qw/Class::Data::Inheritable Class::Accessor::Fast/; |
85 | |
86 | package GoesBang; |
87 | use base qw/Component1 Component2/; |
88 | |
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89 | Any situation like this will cause your application to fail to start. |
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90 | |
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91 | For additional documentation about this issue, and how to resolve it, see |
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92 | L<Class::C3::Adopt::NEXT>. |
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93 | |
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94 | =head2 Components which inherit from Moose::Object before Catalyst::Component |
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95 | |
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96 | Moose components which say: |
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97 | |
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98 | package TestApp::Controller::Example; |
99 | use Moose; |
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100 | extends qw/Moose::Object Catalyst::Component/; |
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101 | |
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102 | to use the constructor provided by Moose, while working (if you do some hacks |
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103 | with the C< BUILDARGS > method), will not work with Catalyst 5.80 as |
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104 | C<Catalyst::Component> inherits from C<Moose::Object>, and so C< @ISA > fails |
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105 | to linearize. |
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106 | |
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107 | The fix for this is to not inherit directly from C<Moose::Object> |
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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 |
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111 | to detect the version of Catalyst your application is running, and deal |
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112 | with it appropriately. |
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113 | |
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114 | You will also see this issue if you do the following: |
115 | |
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116 | package TestApp::Controller::Example; |
117 | use Moose; |
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118 | use base 'Catalyst::Controller'; |
119 | |
120 | as C< use base > appends to @ISA. |
121 | |
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122 | The correct way to use Moose in a component in a both forward and backwards |
123 | compatible way is: |
124 | |
125 | package TestApp::Controller::Root; |
126 | use Moose; |
127 | BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever |
128 | |
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129 | Note that the C< extends > declaration needs to occur in a begin block for |
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130 | L<attributes> to operate correctly. |
131 | |
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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 |
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134 | attributes, then they need to be made lazy to correctly initialize. |
135 | |
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 |
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139 | (although BUILDARGS is not). |
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140 | |
141 | If you depend on Catalyst 5.8, then B<all> Moose features work as expected. |
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142 | |
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143 | =head3 use Moose in MyApp |
144 | |
145 | Similar to the above, this will also fail: |
146 | |
147 | package MyApp; |
148 | use Moose; |
149 | use Catalyst qw/ |
150 | ConfigLoader |
151 | /; |
152 | __PACKAGE__->setup; |
153 | |
154 | If you need to use Moose in your application class (e.g. for method modifiers |
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155 | etc.) then the correct technique is: |
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156 | |
157 | package MyApp; |
158 | use Moose; |
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159 | use Catalyst; |
160 | |
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161 | extends 'Catalyst'; |
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162 | |
163 | __PACKAGE__->config( name => 'MyApp' ); |
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164 | __PACKAGE__->setup(qw/ |
165 | ConfigLoader |
166 | /); |
167 | |
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168 | =head2 Anonymous closures installed directly into the symbol table |
169 | |
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: |
173 | |
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174 | # Original code, likely to break: |
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175 | my $full_method_name = join('::', $package_name, $method_name); |
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176 | *$full_method_name = sub { ... }; |
177 | |
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178 | # Fixed Code |
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179 | use Sub::Name 'subname'; |
180 | my $full_method_name = join('::',$package_name, $method_name); |
181 | *$full_method_name = subname $full_method_name, sub { ... }; |
182 | |
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183 | Additionally, you can take advantage of Catalyst's use of L<Class::MOP> and |
184 | install the closure using the appropriate metaclass. Example: |
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185 | |
186 | use Class::MOP; |
187 | my $metaclass = Moose::Meta::Class->initialize($package_name); |
188 | $metaclass->add_method($method_name => sub { ... }); |
189 | |
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190 | =head2 Hooking into application setup |
191 | |
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192 | To execute code during application start-up, the following snippet in MyApp.pm |
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193 | used to work: |
194 | |
195 | sub setup { |
196 | my ($class, @args) = @_; |
197 | $class->NEXT::setup(@args); |
198 | ... # things to do after the actual setup |
199 | } |
200 | |
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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. |
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205 | |
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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. |
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210 | |
211 | The right way to do it is this: |
212 | |
213 | after setup_finalize => sub { |
214 | ... # things to do after the actual setup |
215 | }; |
216 | |
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217 | The setup_finalize hook was introduced as a way to avoid this issue. |
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218 | |
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219 | =head2 Components with a new method which returns false |
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220 | |
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221 | Previously, if you had a component which inherited from Catalyst::COMPONENT, |
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222 | but overrode the new method to return false, then your class's configuration |
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223 | would be blessed into a hash on your behalf, and this would be returned from |
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224 | the COMPONENT method. |
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225 | |
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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 |
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229 | functionality and/or Moose attributes to perform any construction work |
230 | necessary for your class. |
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231 | |
232 | =head2 __PACKAGE__->mk_accessor('meta'); |
233 | |
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234 | Won't work due to a limitation of L<Moose>. This is currently being fixed |
235 | inside Moose. |
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236 | |
237 | =head2 Class::Data::Inheritable side effects |
238 | |
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239 | Previously, writing to a class data accessor would copy the accessor method |
240 | down into your package. |
241 | |
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242 | This behavior has been removed. While the class data is still stored |
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243 | per-class, it is stored on the metaclass of the class defining the accessor. |
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244 | |
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245 | Therefore anything relying on the side effect of the accessor being copied down |
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246 | will be broken. |
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247 | |
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248 | The following test demonstrates the problem: |
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249 | |
250 | { |
251 | package BaseClass; |
252 | use base qw/Class::Data::Inheritable/; |
253 | __PACKAGE__->mk_classdata('foo'); |
254 | } |
255 | |
256 | { |
257 | package Child; |
258 | use base qw/BaseClass/; |
259 | } |
260 | |
261 | BaseClass->foo('base class'); |
262 | Child->foo('sub class'); |
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263 | |
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264 | use Test::More; |
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265 | isnt(BaseClass->can('foo'), Child->can('foo')); |
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266 | |
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267 | =head2 Extending Catalyst::Request or other classes in an ad-hoc manner using mk_accessors |
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268 | |
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269 | Previously, it was possible to add additional accessors to Catalyst::Request |
270 | (or other classes) by calling the mk_accessors class method. |
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271 | |
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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 |
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274 | Catalyst objects. |
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275 | |
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276 | =head2 Confused multiple inheritance with Catalyst::Component::COMPONENT |
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277 | |
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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. |
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282 | |
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283 | If a COMPONENT method is detected in the inheritance hierarchy to the right |
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284 | hand side of Catalyst::Component::COMPONENT, then the following warning |
285 | message will be emitted: |
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286 | |
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287 | There is a COMPONENT method resolving after Catalyst::Component |
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288 | in ${next_package}. |
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289 | |
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290 | The correct fix is to re-arrange your class's inheritance hierarchy so that the |
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291 | COMPONENT method you would like to inherit is the first (left-hand most) |
292 | COMPONENT method in your @ISA. |
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293 | |
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294 | =head1 WARNINGS |
295 | |
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296 | =head2 Catalyst::Base |
297 | |
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298 | Any code using L<Catalyst::Base> will now emit a warning; this |
299 | module will be removed in a future release. |
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300 | |
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301 | =head2 Methods in Catalyst::Dispatcher |
302 | |
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303 | The following methods in Catalyst::Dispatcher are implementation |
304 | details, which may change in the 5.8X release series, and therefore their use |
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305 | is highly deprecated. |
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306 | |
307 | =over |
308 | |
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309 | =item tree |
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310 | |
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311 | =item dispatch_types |
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312 | |
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313 | =item registered_dispatch_types |
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314 | |
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315 | =item method_action_class |
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316 | |
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317 | =item action_hash |
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318 | |
319 | =item container_hash |
320 | |
321 | =back |
322 | |
323 | The first time one of these methods is called, a warning will be emitted: |
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324 | |
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325 | Class $class is calling the deprecated method Catalyst::Dispatcher::$public_method_name, |
326 | this will be removed in Catalyst 5.9X |
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327 | |
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328 | You should B<NEVER> be calling any of these methods from application code. |
329 | |
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330 | Plugin authors and maintainers whose plugins currently call these methods |
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331 | should change to using the public API, or, if you do not feel the public API |
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332 | adequately supports your use case, please email the development list to |
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333 | discuss what API features you need so that you can be appropriately supported. |
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334 | |
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335 | =head2 Class files with names that don't correspond to the packages they define |
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336 | |
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337 | In this version of Catalyst, if a component is loaded from disk, but no |
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338 | symbols are defined in that component's name space after it is loaded, this |
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339 | warning will be issued: |
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340 | |
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341 | require $class was successful but the package is not defined. |
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342 | |
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343 | This is to protect against confusing bugs caused by mistyping package names, |
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344 | and will become a fatal error in a future version. |
345 | |
346 | Please note that 'inner packages' (via L<Devel::InnerPackage>) are still fully |
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347 | supported; this warning is only issued when component file naming does not map |
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348 | to B<any> of the packages defined within that component. |
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349 | |
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350 | =head2 $c->plugin method |
351 | |
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352 | Calling the plugin method is deprecated, and calling it at run time is B<highly |
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353 | deprecated>. |
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354 | |
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355 | Instead you are recommended to use L< Catalyst::Model::Adaptor > or similar to |
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356 | compose the functionality you need outside of the main application name space. |
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357 | |
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358 | Calling the plugin method will not be supported past Catalyst 5.81. |
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359 | |
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360 | =cut |
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361 | |