Configuration Library
, (*1)
This package provides a class to manage hierarchical data.
A common use case is configuration data., (*2)
Note that this package does not provide any readers or writers
for config files of different formats.
Instead it wraps php arrays
and provides easier access to its values., (*3)
Why?
I was tired of using too many isset throghout all my code. The main
advantage of this library is, that you can request
an arbitrary deeply nested value, and provide a default value which
should be returned in case the requested value does not exist:, (*4)
$myConfig = [
'root' => [
'specific' => ['key' => 'val'],
],
];
// plain php is a bit ugly...
$theSpecific = isset($myConfig['root']['specific']['key']) ?
$myConfig['root']['specific']['key'] : null;
$theGeneral = isset($myConfig['root']['key']) ?
$myConfig['root']['key'] : false;
// ... but with a `Config` it looks nicer:
$config = new Ckr\Config\Config($myConfig);
$theSpecific = $config->get('root/specific/key');
$theGeneral = $config->get('root/key', false);
Actually, if you're using PHP7, this problem is solved:, (*5)
// valid code in PHP7
$theSpecific= $myConfig['root']['specific']['key'] ?? null;
$theGeneral = $myConfig['root']['key'] ?? false;
However, as I prefer to specify the path as root/specific/key instead
of ['root']['specific']['key'], I still use this library in my
PHP7 projects., (*6)
Usage
You start with a hierarchical data structure, defined as multi dimensional array:, (*7)
$myConfig = [
'mode' => 'production',
'logging' => [
'factory' => 'Your\\Logging\\Factory',
'loggers' => [
[
'type' => 'file',
'path' => '/path/to/logs',
'level' => 'warn',
],
[
'type' => 'email',
'addr' => 'someone@somewhere.com',
'level' => 'critical',
]
],
]
];
Then you can wrap it in a Config object:, (*8)
use Ckr\Config\Config;
$c = new Config($myConfig);
You can ask for a simple value with get:, (*9)
$mode = $c->get('mode', 'dev');
In the example above, "dev" is the default mode. It is returned, if the key 'mode'
does not exist in the config data., (*10)
You can ask for a value which is nested in a child array by providing a path of keys, separated
by a Slash /:, (*11)
$loggingFactoryClass = $c->get('logging/factory');
If any of the used path parts (keys) don't exist, the default value (null if
not explicitly specified) is returned., (*12)
Say you want to use all of the logging data, e.g. to instantiate your logging instance.
For this, you can get a child config object:, (*13)
$loggingConfig = $c->child('logging'); /* @var $loggingConfig Config */
// we can now provide only the relevant data to thr logging factory
$myLoggingFactory = new $loggingFactoryClass;
$logger = $myLoggingFactory->create($loggingConfig);
// the logging factory "sees" only the data of the "logging" child array
public function create(Config $cfg)
{
$loggers = $cfg->get('loggers'); // $loggers is an array
foreach ($loggers as $logger) { /* ... */ }
// ...
}
To summarize:, (*14)
-
Config::get will always return the value as it was defined originally. No matter, if the
value is an array, a class instance, a function or a scalar value.
-
Config::child expects the given path to point to an (associative) array. It wraps this
array in a Config and returns that object.
A new value can be set using Config::set:, (*15)
$newConfig = $c->set('logging/factory', 'AnotherFactoryClass');
This method returns a new instance with a specific part of the config updated (or newly set).
This may be useful if you want to construct a complete configuration object
in multiple steps from different parts of your code,
e.g. to allow different modules to register their configuration or factories.
In the above example, $newConfig has a value of 'AnotherFactoryClass' at the path
logging/factory, where the $c instance is not modified and still has the old value.
(Note that this behaviour is new in Version 2.0, former versions did update the data in place)., (*16)
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