Marcel Grünauer > Hook-Modular > Hook::Modular

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Module Version: 1.101050   Source  

NAME ^

Hook::Modular - Making pluggable applications easy

VERSION ^

version 1.101050

SYNOPSIS ^

In some_config.yaml

  global:
    log:
      level: error
    cache:
      base: /tmp/test-hook-modular
    # plugin_namespace: My::Test::Plugin
  
  plugins:
    - module: Some::Printer
      config:
        indent: 4
        indent_char: '*'
        text: 'this is some printer'

here is the plugin:

  package My::Test::Plugin::Some::Printer;
  use warnings;
  use strict;
  use parent 'Hook::Modular::Plugin';
  
  sub register {
      my ($self, $context) = @_;
      $context->register_hook($self,
        'output.print' => $self->can('do_print'));
  }
  
  sub do_print { ... }

And this is some_app.pl

  use parent 'Hook::Modular';

  use constant PLUGIN_NAMESPACE => 'My::Test::Plugin';

  sub run {
    my $self = shift;
    $self->SUPER::run(@_);
    ...
    $self->run_hook('output.print', ...);
    ...
  }

  main->bootstrap(config => $config_filename);

But also see Hook::Modular::Builder for a domain-specific language to build a configuration.

DESCRIPTION ^

Hook::Modular makes writing pluggable applications easy. Use a config file to specify which plugins you want and to pass options to those plugins. The program to support those plugin then subclasses Hook::Modular and bootstraps itself. This causes the plugins to be loaded and registered. This gives each plugin the chance to register callbacks for any or all hooks the program offers. The program then runs the hooks in the order it desires. Each time a hook is run, all the callbacks the plugins have registered with this particular hook are run in order.

Hook::Modular does more than just load and call plugins, however. It also supports the following concepts:

Cache

Plugins can cache their settings. Cached items can also expire after a given time.

Crypt

Hook::Lexwrap can go over your config file and encrypt any passwords it finds (as determined by the key password). It will then rewrite the config file and make a backup of the original file. Encrypting and rewriting is turned off by default, but subclasses can enable it, or you can enable it from a config file itself.

At the moment, encrypting is rather basic: The passwords are only turned into base64.

Rules

Hook::Modular supports rule-based dispatch of plugins.

METHODS ^

new

  my $obj = Hook::Modular->new(config => $config_file_name);

Creates a new object and initializes it. The arguments are passed as a named hash. Valid argument keys:

config

Reads or sets the global configuration.

If the value is a simple string, it is interpreted as a filename. If the file is readable, it is loaded as YAML. If the filename is -, the configuration is read from STDIN.

If the value is a scalar reference, the dereferenced value is assumed to be YAML and is loaded.

If the value is a hash reference, the configuration is cloned from that hash reference.

Also see Hook::Modular::Builder for a domain-specific language to build a configuration.

The constructor also sets the application-wide configuration, which can be accessed using conf(), to the global part of the configuration data that has been passed to the constructor. This configuration is then augmented in various ways:

log level
  my $level = $self->conf->{log}{level}

The log level is set to debug, if it hasn't been set by the configuration data already.

In the config file, you can specify it this way:

  global:
    log:
      level: info
log encoding
  my $encoding = $self->conf->{log}{encoding}

The log encoding is set to the current terminal's encoding, if it hasn't been set by the configuration data already.

In the config file, you can specify it this way:

  global:
    log:
      level: info
plugin_namespace
  my $ns = $self->conf->{plugin_namespace};

The default plugin namespace is set to whatever the class defines as the PLUGIN_NAMESPACE constant, if the configuration data hasn't set it already. See the documentation of PLUGIN_NAMESPACE for details.

should_rewrite_config
  my $should_rewrite_config = $self->conf->{should_rewrite_config};

If the configuration data hasn't set it already to either 0 or 1, config file rewriting is turned off. See the documentation of SHOULD_REWRITE_CONFIG for details.

rule_namespaces

If the config file specifies any rule namespaces, they are added to the default rule namespaces. See the documentation of add_to_rule_namespaces() for details.

context, set_context

  my $context = $self->context;
  $self->set_context($context);

Gets and sets (respectively) the global context. It is singular; each program has only one context. This can be used to communicate between the plugins.

conf

  my %conf = $self->conf;
  my $plugin_path = $self->conf->{plugin_path} || [];
  $self->conf->{log}{level} = 'debug';

Returns a hash that has the application-wide configuration. It is set during new() from the global section of the configuration data and augmented with various other settings.

PLUGIN_NAMESPACE

  package My::TestApp;
  use parent 'Hook::Modular';
  use constant PLUGIN_NAMESPACE => 'My::Test::Plugin';

A constant that specifies the namespace that is prepended to plugin names found in the configuration. Defaults to Hook::Modular::Plugin. Subclasses can and probably should override this value. For example, if the plugin namespace is set to My::Test::Plugin and the config file specifies a plugin with the name Some::Printer, we will try to load My:::Test::Plugin::Some::Printer.

In the config file, you can specify it this way:

  global:
    plugin_namespace: My::Test::Plugin

SHOULD_REWRITE_CONFIG

  package My::TestApp;
  use parent 'Hook::Modular';
  use constant SHOULD_REWRITE_CONFIG => 1;

Hook::Modular can rewrite your config file, for example, to turn passwords into encrypted forms so they are not easily readable in the plain text. This behaviour is turned off by default, but the config file, or a subclass of Hook::Modular, can turn it on. In a config file, specify it this way:

In the config file, you can specify it this way:

  global:
    should_rewrite_config: 1

add_to_rule_namespace

  $self->add_to_rule_namespaces(
    qw/Some::Rule::Namespace Other::Rule::Namespace/);

Hook::Modular supports multiple rule namespace, that is, package prefixes that are used when looking for rule classes. The reason to allow multiple rule namespace is that Hook::Modular has some rules, and your subclass might well define its own rules, so Hook::Modular needs to know which package it might find rules in.

There is only one list of rule namespace per program. To add to rule namespaces in your program, don't access conf() directly, but use the proper class methods to do so: add_to_rule_namespaces() and rule_namespaces().

You can add to rule namespaces using the config file like this:

  global:
    rule_namespaces:
      - Some::Thing::Rule
      - Other::Thing::Rule

or, if you only want to add one rule namespace:

  global:
    rule_namespaces: Some::Thing::Rule

rule_namespaces

  my @ns = $self->rule_namespaces;

Returns the list of rule namespaces. See the documentation of add_to_rule_namespaces for details.

add_plugin_path

FIXME

add_rewrite_task

FIXME

add_to_rule_namespaces

FIXME

autoload_plugin

FIXME

dumper

FIXME

error

FIXME

extract_package

FIXME

home_dir

FIXME

init

FIXME

is_loaded

FIXME

load_cache

FIXME

load_plugin

FIXME

load_plugins

FIXME

register_hook

FIXME

rewrite_config

FIXME

run

FIXME

run_hook

FIXME

run_hook_once

FIXME

run_main

FIXME

should_log

FIXME

INSTALLATION ^

See perlmodinstall for information and options on installing Perl modules.

BUGS AND LIMITATIONS ^

No bugs have been reported.

Please report any bugs or feature requests through the web interface at http://rt.cpan.org/Public/Dist/Display.html?Name=Hook-Modular.

AVAILABILITY ^

The latest version of this module is available from the Comprehensive Perl Archive Network (CPAN). Visit http://www.perl.com/CPAN/ to find a CPAN site near you, or see http://search.cpan.org/dist/Hook-Modular/.

The development version lives at http://github.com/hanekomu/Hook-Modular/. Instead of sending patches, please fork this project using the standard git and github infrastructure.

AUTHORS ^

  Marcel Gruenauer <marcel@cpan.org>
  Tatsuhiko Miyagawa <miyagawa@bulknews.net>

COPYRIGHT AND LICENSE ^

This software is copyright (c) 2007 by Marcel Gruenauer.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

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