Provided by: libconfig-onion-perl_1.007-1_all 
NAME
Config::Onion - Layered configuration, because configs are like ogres
VERSION
version 1.007
SYNOPSIS
my $cfg = Config::Onion->new;
my $cfg = Config::Onion->set_default(db => {name => 'foo', password => 'bar'});
my $cfg = Config::Onion->load('/etc/myapp', './myapp');
my $cfg = Config::Onion->load('/etc/myapp', './myapp', {use_ext => 1, filter => \&filter});
my $cfg = Config::Onion->load_glob('./plugins/*');
my $cfg = Config::Onion->load_glob('./plugins/*', {force_plugins => ['Config::Any::YAML']});
$cfg->set_default(font => 'Comic Sans');
$cfg->load('config');
$cfg->load_glob('conf.d/myapp*');
$cfg->set_override(font => 'Arial');
my $dbname = $cfg->get->{db}{name};
my $plain_hashref_conf = $cfg->get;
my $dbpassword = $plain_hashref_conf->{db}{password};
DESCRIPTION
All too often, configuration is not a universal or one-time thing, yet most configuration-
handling treats it as such. Perhaps you can only load one config file. If you can load
more than one, you often have to load all of them at the same time or each is stored
completely independently, preventing one from being able to override another.
Config::Onion changes that.
Config::Onion stores all configuration settings in four layers: Defaults, Main, Local, and
Override. Each layer can be added to as many times as you like. Within each layer,
settings which are given multiple times will take the last specified value, while those
which are not repeated will remain untouched.
$cfg->set_default(name => 'Arthur Dent', location => 'Earth');
$cfg->set_default(location => 'Magrathea');
# In the Default layer, 'name' is still 'Arthur Dent', but 'location' has
# been changed to 'Magrathea'.
Regardless of the order in which they are set, values in Main will always override values
in the Default layer, the Local layer always overrides both Default and Main, and the
Override layer overrides all the others.
The design intent for each layer is:
• Default
Hardcoded default values to be used when no further configuration is present
• Main
Values loaded from standard configuration files shipped with the application
• Local
Values loaded from local configuration files which are kept separate to prevent them
from being overwritten by application upgrades, etc.
• Override
Settings provided at run-time which take precendence over all configuration files,
such as settings provided via command line switches
If a higher-priority layer wishes to completely remove a hash entry made by a lower-
priority layer (i.e., delete the hash key, not just set it to an empty value), it can do
so by setting the value to "!DELETE!". This only applies to hash entries, not array
values, as the entire array already needs to be overwritten to make any changes to it.
Also, if, for some reason, the configuration contains objects, the contents of those
objects will be ignored for the sake of encapsulation. Only unblessed hashes are cleaned
in this manner.
METHODS
new
Returns a new, empty configuration object.
load(@file_stems) =head2 load(@file\_stems, {...})
Loads files matching the given stems using "Config::Any->load_stems" into the Main layer.
Also concatenates ".local" to each stem and loads matching files into the Local layer.
e.g., "$cfg->load('myapp')" would load "myapp.yml" into Main and "myapp.local.js" into
Local. All filename extensions supported by "Config::Any" are recognized along with their
corresponding formats.
An optional hash ref final argument can be provided to override the default option
"use_ext => 1" passed to "Config::Any". All options supported by "Config::Any" are
supported except flatten_to_hash. See "Config::Any->load_files" documentation for
available options.
load_glob(@globs) =head2 load_glob(@globs, {...})
Uses the Perl "glob" function to expand each parameter into a list of filenames and loads
each file using "Config::Any". Files whose names contain the string ".local." are loaded
into the Local layer. All other files are loaded into the Main layer.
An optional hash ref final argument can be provided to override the default option
"use_ext => 1" passed to "Config::Any". All options supported by "Config::Any" are
supported except flatten_to_hash. See "Config::Any->load_files" documentation for
available options.
set_default([\%settings,...,] %settings)
set_override([\%settings,...,] %settings)
Imports %settings into the Default or Override layer. Accepts settings both as a plain
hash and as hash references, but, if the two are mixed, all hash references must appear at
the beginning of the parameter list, before any non-hashref settings.
PROPERTIES
cfg
get
Returns the complete configuration as a hash reference.
default
main
local
override
These properties each return a single layer of the configuration. This is not likely to
be useful other than for debugging. For most other purposes, you probably want to use
"get" instead.
prefix_key
If set, enables the Prefix Structures functionality described below when using the "load"
or "load_glob" methods. The value of "prefix_key" specifies the name of the key under
which the prefix structure may be found.
Default value is "undef".
Prefix Structures
If you find that your configuration structure is becoming unwieldy due to deeply-nested
structures, you can define a file-specific "prefix structure" and all other settings
within that file will be loaded as children of the prefix structure. For example, if your
main program uses
$cfg = Config::Onion->new(prefix_key => '_prefix');
$cfg->load("myapp/config");
and "myapp/config.yml" contains
_prefix:
foo:
bar:
baz: 1
then $cfg will contain the configuration
foo:
bar:
baz: 1
Note that the top-level "prefix_key" is removed.
There are some limitations on the prefix structure, in order to keep it sane and
deterministic. First, the prefix structure may only contain hashes. Second, each hash
must contain exactly one key. Finally, the value associated with the final key must be
left undefined.
BUGS AND LIMITATIONS
No bugs have been reported.
Please report any bugs or feature requests at
<https://github.com/dsheroh/Config-Onion/issues>
AUTHOR
Dave Sherohman <dsheroh@cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2012 by Lund University Library.
This is free software; you can redistribute it and/or modify it under the same terms as
the Perl 5 programming language system itself.