Difference between #9 and #8 of Yii registry, how to use it, does it exist at all?

Introduction
------------------
From time to time people ask about registry...

If you coming to Yii with experience with Zend Framework for example,
most likely you get used to
~~~
[php]
Zend_Registry::get('paramName');
Zend_Registry::set('paramName');
~~~

Registry in Yii
---------------

In Yii you also has it

set variable:
~~~
[php]
Yii::app()->params['abc'] = 123;
~~~

get variable:
~~~
[php]
echo Yii::app()->params['abc'];
~~~

get all defined variables:
~~~
[php]
Yii::app()->getParams()
~~~

it is the same like use
~~~
[php]
Yii::app()->params
~~~

Smart to use with **CVarDumper**:
~~~
[php]
CVarDumper::dump(Yii::app()->getParams(), 10, true);
~~~

If You use **CVarDumper**, it looks like this:
~~~
[php]
CAttributeCollection#1
(
    [caseSensitive] => true
    [CMap:_d] => array
    (
        'abc' => 123
        'a' => 123
        'c' => 1316855672
        'd' => 'cookie'
    )
    [CMap:_r] => false
    [CComponent:_e] => null
    [CComponent:_m] => null
)
~~~

You can also do mass assignment via array 

~~~
[php]
Yii::app()->setParams(array('a' => 123, 'c' => time(), 'd' =>
'cookie'));
~~~

To unset some key, you can use
~~~
[php]
unset(Yii::app()->params['abc'])
~~~

CMap
------------------
Because the params is CMap instance

You can use the Cmap methods

for example:

get total of variables defined:
~~~
[php]
echo Yii::app()->params->getCount();
~~~
for the example above will return **4**

It is the same like
~~~
[php]
Yii::app()->params->count; or Yii::app()->params->count();
~~~

You can get the keys

~~~
[php]
Yii::app()->params->keys;
~~~

Will return array like this:
~~~
[php]
    '0' => 'abc'
    '1' => 'a'
    '2' => 'c'
    '3' => 'd'
~~~

I mentioned the unset before, but you also can use
~~~
[php]
 Yii::app()->params->remove('abc');
~~~


You can delete all params via
~~~
[php]
 Yii::app()->params->clear();
~~~

Tip 1
----
**->params** is the same like **->getParams()** method
**params['sdf']=$val** is the same like calling **setParams('sdf',$val)**;
This is right to all the framework, magic method take care all the
"magic" behind it
Just add for example in Controller that extends CController **getSomething** and
you can use **$this->something** ...

Tip 2
-----
For most of you this is trivial, but:
The initial params don't come from nowhere
In **configs/main.php**
You have the params array
~~~
[php]
'params'=>array('abc' => 123),
~~~

I personally like to add in config folder

**params.php**

And than you can replace the above line with:

For php > 5.3
~~~
[php]
'params'=>require( __DIR__ .'/params.php'),
~~~

for < 5.3 you should't use 

~~~
[php]
__DIR__
~~~

, replace it with 

~~~
[php]
dirname(__FILE__)
~~~


And the **config/params.php** contains:
~~~
[php]
<?php
return array(
	'abc' =>123,
);
~~~

Addition 1: Yii global state
----------------------------

The params array, can be good registry for the current life cycle.
but yii also has something called "globalstate", it allow you save the
data "forever"

CApplication has 3 methods:<br>
**getGlobalState**(string **$key**, mixed **$defaultValue**=NULL)<br>
**setGlobalState**(string **$key**, mixed $value, mixed
**$defaultValue**=NULL)<br>
**clearGlobalState**()<br>

every thing you set via setGlobalState will be saved in runtime/global.bin in
serialized form

Some common component that use it is CSecurityManager for validation key


Links
-----
[Russian version](http://resurtm.kz/registry-in-yii)