Provided by: libbadger-perl_0.16-3_all 
NAME
Badger::Class::Config - class mixin for configuration
SYNOPSIS
package Your::Module;
# via Badger::Class
use Badger::Class
base => 'Badger::Base',
accessors => 'foo bar baz wig woot toot zoot zang',
config => [
'foo', # optional item
'bar!', # mandatory item
'baz=42', # item with default
'wig|wam|bam', # item with aliases
'woot|pkg:WOOT', # fallback to $WOOT pkg var
'toot|class:WOOT', # fallback to $WOOT class var
'zoot|method:ZOOT', # fallback to ZOOT() method/constant
'zing|zang|pkg:ZING=99', # combination of above
];
sub init {
my ($self, $config) = @_;
# call the configure() method provided by the above
$self->configure($config);
return $self;
}
DESCRIPTION
This class mixin module allows you to define configuration parameters for an object class.
It exports a configure() method which can be used to initialise your object instances.
Please note that the scope of this module is intentionally limited at present. It should
be considered experimental and subject to change.
Configuration Options
Configuration options for a module can be defined as import options to
"Badger::Class::Config".
package Your::Module;
use base 'Badger::Base';
use Badger::Class::Config 'foo', 'bar';
For convenience, multiple items can be specified in a single whitespace delimited string.
use Badger::Class::Config 'foo bar';
More complex configurations can be specified using list and hash references, but we'll
keep things simple for now.
Using the module as shown here has two immediate effects. The first is that the
$CONFIG_SCHEMA package variable will be defined in "Your::Module" containing a reference
to the configuration schema for your module. This schema contains information about the
configuration items which in this example are "foo" and "bar". The second effect is to
define a configure() method which uses this schema to configure your object using the
configuration options passed to the constructor method. You can call this method from your
init() method (if you're using Badger::Base) or from your own construction or
initialisation methods.
sub init {
my ($self, $config) = @_;
$self->configure($config);
return $self;
}
The configure() method is intentionally simple, although flexible. It doesn't attempt to
assert that any configuration items are of the correct type or validate the values in any
way. If the relevant values are defined in the $config hash then they will be copied into
$self. Otherwise they are ignored.
If a configuration item is mandatory then add a "!" at the end of the name. If no value
is defined for this item then the configure() method will throw an exception.
use Badger::Class::Config 'foo! bar!'; # mandatory items
A default value can be provided using "=";
use Badger::Class::Config 'foo=10 bar=20'; # default values
Aliases for the configuration item can be provided using "|"
use Badger::Class::Config 'foo|Foo|FOO'; # aliases for 'foo'
As well as looking for items in the $config hash array, you can search for package
variables (in the current package), class variables (in the current package or those of
all base class), environment variables, and call object methods.
use Badger::Class::Config
'foo|pkg:FOO', # fallback to $FOO package var
'bar|class:BAR', # fallback to $BAR class var
'baz|env:BAZ', # fallback to $BAZ environment var
'bam|method:BAM'; # fallback to BAM() method
'wam|target:slam'; # fallback to $target->{ slam }
Bear in mind that Perl implements constants using subroutines. Thus, you can access a
constant defined in a package/class by calling it as a method. So if you have a constant
defined in the module that you want to use then specify it using the "method:" prefix.
TODO: more on that
Detailed Specification
The syntax for defining configuration options described above is a short-cut to the more
detailed specification used to generate a configuration scheme for the configure() method
to use. You can use the more detailed specification if you prefer:
use Badger::Class::Config
{
foo => {
required => 1,
default => 10,
fallback => ['class:FOO', 'env:FOO'],
},
bar => {
required => 1,
default => 20,
fallback => ['class:BAR', 'env:BAR'],
},
};
You can mix and match simple and detailed specifications by specifying them as items in a
list reference. Each configuration option should be defined as a separate item (i.e. you
can't merge multiple items into a single whitespace delimited string). Simple definitions
are specified using strings, complex definitions using hash reference. Note that the name
of the option must be specified explicitly in the hash array when used this way.
use Badger::Class::Config
[
'foo|class:FOO!',
{
name => 'bar',
required => 1,
default => 20,
fallback => ['class:BAR', 'env:BAR'],
},
];
Badger::Class Hook
The Badger::Class module implements a config hook which interfaces to this module. You
can specify a single string to define multiple configuration items in one go:
use Badger::Class
base => 'Badger::Base',
config => 'foo! bar=10 baz|class:BAZ=20';
Or a reference to a hash array or list containing individually defined configuration
items.
use Badger::Class
base => 'Badger::Base',
config => [
'foo!',
'bar=10',
'baz|class:BAZ=20'
];
METHODS
schema()
This method is used internally to define a configuration schema. It exports it as the
$CONFIG_SCHEMA package variable into the calling module.
configure($config,$target)
This method is exported the calling module to perform the configuration process. It used
the configuration schema stored in the $CONFIG_SCHEMA package variable by the schema()
method. It is typically called from a construction or initialisation method.
The first argument should be a reference to a hash array of configuration options. The
second should be a reference to a hash array or hash-based object into which the
configuration values can be copied. If this is not specified then the method defaults to
updating the $self object reference passed as the first implicit argument.
sub init {
my ($self, $config) = @_;
$self->configure($config);
return $self;
}
configure_pkg()
This method is used internally to look up package variables for configuration options.
configure_class()
This method is used internally to look up class variables for configuration options.
Class variables are package variables in the current package or those of any of its base
classes.
configure_env()
This method is used internally to look up environment variables for configuration options.
configure_method()
This method is used internally to call object methods to return default configuration
values.
configure_target()
This method is used internally to look inside the target object or hash array to return
default configuration values.
fallback()
This method is used internally to generate fallbacks for configuration values.
AUTHOR
Andy Wardley <http://wardley.org/>
COPYRIGHT
Copyright (C) 2008-2009 Andy Wardley. All Rights Reserved.
This module is free software; you can redistribute it and/or modify it under the same
terms as Perl itself.