1Catalyst::Manual::InterUnsaelrs(C3o)ntributed Perl DocumCeanttaaltyisotn::Manual::Internals(3)
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NAME

6       Catalyst::Manual::Internals - Catalyst Internals
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DESCRIPTION

9       This document provides an overview of the internals of Catalyst.  As
10       Catalyst is still developing rapidly, details may become out of date:
11       please treat this as a guide, and look at the source for the last word.
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13       The coverage is split into initialization and request lifecycle.
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15       Initialization
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17       Catalyst initializes itself in two stages (I may be wrong in some of
18       the details here - AF):
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20       1   When the Catalyst module is imported in the main application module
21           it evaluates any options ("-Debug", "-Engine=XXX") and loads any
22           specified plugins, making the application module inherit from the
23           plugin classes. It also sets up a default log object and ensures
24           that the application module inherits from "Catalyst" and from the
25           selected specialized Engine module.
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27       2   When the application module makes the first call to "__PACK‐
28           AGE__->action()" (implemented in "Catalyst::Engine"), Catalyst
29           automatically loads all components it finds in the $class::Con‐
30           troller, $class::C, $class::Model, $class::M, $class::View and
31           $class::V namespaces (using "Module::Pluggable::Fast").  A table of
32           actions is built up and added to on subsequent calls to "action()".
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34       Request Lifecycle
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36       For each request Catalyst builds a context object, which includes
37       information about the request, and then searches the action table for
38       matching actions.
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40       The handling of a request can be divided into three stages: preparation
41       of the context, processing of the request, and finalization of the
42       response.  These are the steps of a Catalyst request in detail; every
43       step can be overloaded to extend Catalyst.
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45           handle_request
46             prepare
47               prepare_request
48               prepare_connection
49               prepare_query_parameters
50               prepare_headers
51               prepare_cookies
52               prepare_path
53               prepare_body (unless parse_on_demand)
54                 prepare_body_parameters
55                 prepare_parameters
56                 prepare_uploads
57               prepare_action
58             dispatch
59             finalize
60               finalize_uploads
61               finalize_error (if one happened)
62               finalize_headers
63                 finalize_cookies
64               finalize_body
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66       These steps are normally overloaded from engine classes, and may also
67       be extended by plugins.  Extending means using multiple inheritance
68       with NEXT.
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70       The specialized engine classes populate the Catalyst request object
71       with information from the underlying layer ("Apache::Request" or
72       "CGI::Simple") during the prepare phase, then push the generated
73       response information down to the underlying layer during the finalize
74       phase.
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AUTHOR

77       Sebastian Riedel, "sri@oook.de"
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80       This program is free software, you can redistribute it and/or modify it
81       under the same terms as Perl itself.
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85perl v5.8.8                       2007-02-28    Catalyst::Manual::Internals(3)
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