Provided by: libconfig-mvp-slicer-perl_0.302-1_all 
NAME
Config::MVP::Slicer - Extract embedded plugin config from parent config
VERSION
version 0.302
SYNOPSIS
my $slicer = Config::MVP::Slicer->new({
config => $parent->config,
});
# extract a hashref from the parent config without modifying the plugin
my $plugin_config = $slicer->slice($plugin);
# from plugin bundles:
my $plugin_spec = ['Name', 'Package::Name', {default => 'config'}];
# update the hashref
$slicer->merge($plugin_spec);
# with object instances:
my $plugger = App::Plugin::Plugger->new({some => 'config'});
# update 'rw' attributes
$slicer->merge($plugger);
DESCRIPTION
This can be used to extract embedded configurations for other plugins out of larger
(parent) configurations.
A example where this can be useful is plugin bundles (see
Config::MVP::Assembler::WithBundles).
A bundle loads other plugins with a default configuration that works most of the time, but
sometimes you wish you could customize the configuration for one of those plugins without
having to remove the plugin from the bundle and re-specify it separately.
# mvp config file
[@MyBundle]
Other::Plugin.setting = new value
Now you can accept customizations to plugins into your bundle config and separate them out
using this module.
ATTRIBUTES
config
This is the main/parent configuration hashref that contains embedded plugin
configurations.
match_name
This is coderef that determines if a configuration line matches a plugin's name.
It can be customized by passing an alternate subroutine reference to the constructor.
The sub will receive two arguments:
• The plugin name portion of the configuration line
• The name of the plugin being worked on (provided to "slice", for instance).
The default returns true if the current plugin name matches the name from the config line
regardless of any leading "@Bundle/" prefixes in the plugin name (as this is a common
convention for bundles).
Obviously if the "@Bundle/" prefix is specified in the configuration then it is required
to be there for the default sub to match (but multiple other "@Bundle/" prefixes will be
allowed before it).
# configuration line: "Foo.attr = value"
$slicer->match_name("Foo", "Foo"); # true
$slicer->match_name("Foo", "@Bar/Foo"); # true
$slicer->match_name("Foo", "Bar"); # false
# configuration line: "@Bar/Foo.attr = value"
$slicer->match_name("@Bar/Foo", "Foo"); # false
$slicer->match_name("@Bar/Foo", "@Bar/Foo"); # true
$slicer->match_name("@Bar/Foo", "@Baz/@Bar/Foo"); # true
$slicer->match_name("@Bar/Foo", "@Baz/Foo"); # false
Subclasses can define "_build_match_name" (which should return a "sub") to overwrite the
default.
match_package
This works like "match_name" except that the configuration line is compared to the
plugin's package (class).
The default returns true if the two values are equal and false otherwise.
If you want to match by package rather than name and you expand packages with (for
example) a string prefix you may need to set this to something like:
match_package => sub { rewrite_prefix($_[0]) eq $_[1] }
Subclasses can define "_build_match_package" (which should return a "sub") to overwrite
the default.
prefix
Regular expression that should match at the beginning of a key before the module name and
attribute:
# prefix => 'dynamic\.'
# { 'dynamic.Module::Name.attr' => 'value' }
This can be a string or a compiled regular expression ("qr//").
The default is no prefix (empty string '').
separator
A regular expression that will capture the package name in $1 and the attribute name in
$2.
The default ("(.+?)\.(.+?)") separates plugin name from attribute name with a dot:
'Module::Name.attribute'
'-Plugin.attr'
NOTE: The regexp should not be anchored since "separator_regexp" uses it as the middle
piece of a larger regexp (to add "prefix" and the possible array bracket suffix). Also
beware of using a regexp that greedily matches the array bracket suffix as that can
confuse things as well.
METHODS
separator_regexp
Returns a compiled regular expression ("qr//") combining "prefix", "separator", and the
possible trailing array specification ("\[.*?\]").
slice
$slicer->slice($plugin);
Return a hashref of the config arguments for the plugin determined by $plugin.
This is a slice of the "config" attribute appropriate for the plugin passed to the method.
Starting with a config hashref of:
{
'APlug:attr1' => 'value1',
'APlug:second' => '2nd',
'OtherPlug:attr => '0'
}
Passing a plugin instance of 'APlug' (or an arrayref of "['APlug', 'Full::Package::APlug',
{}]") would return:
{
'attr1' => 'value1',
'second' => '2nd'
}
merge
$slicer->merge($plugin, \%opts);
Get the config slice (see "slice"), then attempt to merge it into the plugin.
If $plugin is an arrayref the hashref will be modified. If it is an object it's
attributes should be writable ('rw').
This will append to array references if it was specified as an array or if a preexisting
value is an arrayref.
Returns the modified $plugin for convenience.
Possible options:
• "slice" - A hashref like that returned from "slice". If not present, "slice" will be
called.
plugin_info
$slicer->plugin_info($plugin);
Used by other methods to normalize the information about a plugin. Returns a list of
"($name, $package, \%config)".
If $plugin is an arrayref it will simply dereference it. This can be useful for
processing the results of plugin bundles.
If $plugin is an instance of a plugin that has a "plugin_name" method it will construct
the list from that method, "ref", and the instance itself.
CONFIGURATION SYNTAX
Often configurations come from an "ini" file and look like this:
[PluginName]
option = value
This gets converted to a hashref:
PluginName->new({ option => 'value' });
To embed configuration for other plugins:
[@BigBundle]
bundle_option = value
Bundled::Plugin.option = other value
The simple 'bundle_option' attribute is for @BigBundle, and the bundle can slice out the
"Bundled::Plugin" configuration and merge it in to that plugin's configuration.
Prefixes can be used (see "prefix"). In this example the prefix is set as "plug.".
[@Foo]
plug.Bundled::Plugin.attr = value
Due to limitations of this dynamic passing of unknown options (otherwise known as a hack)
values that are arrays cannot be declared ahead of time by the bundle. You can help out
by specifying that an attribute should be an array:
[@Bar]
Baz.quux[0] = part 1
Baz.quux[1] = part 2
This is required because each line will end up in a hashref:
{ "quux[0]" => "part 1", "quxx[1]" => "part 2" }
The subscripts inside the brackets are used for sorting but otherwise ignored. The
"slice" method will sort the keys (alphabetically) to produce:
{ quux => ["part 1", "part 2"] }
For simplicity the keys are sorted alphabetically because "quux[1.9]" and "quux[1.10]"
probably won't sort the way you intended anyway, so just keep things simple:
[@Bundle]
Plug.attr[0] = part 1
Plug.attr[1] = part 2
Plug.other[09] = part 1
Plug.other[10] = part 2
Plug.alpha[a] = part 1
Plug.alpha[b] = part 2
Plug.alpha[bc] = part 3
Plug.single[] = subscript not required; only used for sorting
SUPPORT
Perldoc
You can find documentation for this module with the perldoc command.
perldoc Config::MVP::Slicer
Websites
The following websites have more information about this module, and may be of help to you.
As always, in addition to those websites please use your favorite search engine to
discover more resources.
• Search CPAN
The default CPAN search engine, useful to view POD in HTML format.
<http://search.cpan.org/dist/Config-MVP-Slicer>
• RT: CPAN's Bug Tracker
The RT ( Request Tracker ) website is the default bug/issue tracking system for CPAN.
<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Config-MVP-Slicer>
• CPAN Ratings
The CPAN Ratings is a website that allows community ratings and reviews of Perl
modules.
<http://cpanratings.perl.org/d/Config-MVP-Slicer>
• CPAN Testers
The CPAN Testers is a network of smokers who run automated tests on uploaded CPAN
distributions.
<http://www.cpantesters.org/distro/C/Config-MVP-Slicer>
• CPAN Testers Matrix
The CPAN Testers Matrix is a website that provides a visual overview of the test
results for a distribution on various Perls/platforms.
<http://matrix.cpantesters.org/?dist=Config-MVP-Slicer>
• CPAN Testers Dependencies
The CPAN Testers Dependencies is a website that shows a chart of the test results of
all dependencies for a distribution.
<http://deps.cpantesters.org/?module=Config::MVP::Slicer>
Bugs / Feature Requests
Please report any bugs or feature requests by email to "bug-config-mvp-slicer at
rt.cpan.org", or through the web interface at
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Config-MVP-Slicer>. You will be
automatically notified of any progress on the request by the system.
Source Code
<https://github.com/rwstauner/Config-MVP-Slicer>
git clone https://github.com/rwstauner/Config-MVP-Slicer.git
AUTHOR
Randy Stauner <rwstauner@cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2011 by Randy Stauner.
This is free software; you can redistribute it and/or modify it under the same terms as
the Perl 5 programming language system itself.