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Merge pull request #3032 from arisk/patch-5

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Update basics.md [skip ci]
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Carsten Brandt
2014-04-09 18:19:02 +02:00
parent 586f5b87b0 6d663bd237
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@ -5,7 +5,7 @@ Basic concepts of Yii
Component and Object Component and Object
-------------------- --------------------
Classes of the Yii framework usually extend from one of the two base classes [[yii\base\Object]] and [[yii\base\Component]]. Classes of the Yii framework usually extend from one of the two base classes [[yii\base\Object]] or [[yii\base\Component]].
These classes provide useful features that are added automatically to all classes extending from them. These classes provide useful features that are added automatically to all classes extending from them.
The [[yii\base\Object|Object]] class provides the [configuration and property feature](../api/base/Object.md). The [[yii\base\Object|Object]] class provides the [configuration and property feature](../api/base/Object.md).
@ -42,12 +42,11 @@ class MyClass extends \yii\base\Object
} }
``` ```
In the above, the last parameter of the constructor must take a configuration array In the above example, the last parameter of the constructor must take a configuration array
which contains name-value pairs for initializing the properties at the end of the constructor. which contains name-value pairs that will be used to initialize the object's properties at the end of the constructor.
You can override the `init()` method to do initialization work that should be done after You can override the `init()` method to do initialization work after the configuration is applied.
the configuration is applied.
By following this convention, you will be able to create and configure a new object By following this convention, you will be able to create and configure new objects
using a configuration array like the following: using a configuration array like the following:
```php ```php
@ -63,13 +62,11 @@ Path Aliases
------------ ------------
Yii 2.0 expands the usage of path aliases to both file/directory paths and URLs. An alias Yii 2.0 expands the usage of path aliases to both file/directory paths and URLs. An alias
must start with a `@` character so that it can be differentiated from file/directory paths and URLs. must start with an `@` symbol so that it can be differentiated from file/directory paths and URLs.
For example, the alias `@yii` refers to the Yii installation directory while `@web` contains base URL for currently For example, the alias `@yii` refers to the Yii installation directory while `@web` contains the base URL for the currently running web application. Path aliases are supported in most places in the Yii core code. For example, `FileCache::cachePath` can accept both a path alias and a normal directory path.
running web application. Path aliases are supported in most places in the Yii core code. For example,
`FileCache::cachePath` can take both a path alias and a normal directory path.
Path alias is also closely related with class namespaces. It is recommended that a path Path aliases are also closely related to class namespaces. It is recommended that a path
alias be defined for each root namespace so that you can use Yii the class autoloader without alias be defined for each root namespace so that Yii's class autoloader can be used without
any further configuration. For example, because `@yii` refers to the Yii installation directory, any further configuration. For example, because `@yii` refers to the Yii installation directory,
a class like `yii\web\Request` can be autoloaded by Yii. If you use a third party library a class like `yii\web\Request` can be autoloaded by Yii. If you use a third party library
such as Zend Framework, you may define a path alias `@Zend` which refers to its installation such as Zend Framework, you may define a path alias `@Zend` which refers to its installation
@ -87,28 +84,25 @@ The following aliases are predefined by the core framework:
Autoloading Autoloading
----------- -----------
All classes, interfaces and traits are loaded automatically at the moment they are used. There's no need to use All classes, interfaces and traits are loaded automatically at the moment they are used. There's no need to use `include` or `require`. It is true for Composer-loaded packages as well as Yii extensions.
`include` or `require`. It is, as well, true for Composer-loaded packages and Yii extensions.
Autoloader works according to [PSR-4](https://github.com/php-fig/fig-standards/blob/master/proposed/psr-4-autoloader/psr-4-autoloader.md). Yii's autoloader works according to [PSR-4](https://github.com/php-fig/fig-standards/blob/master/proposed/psr-4-autoloader/psr-4-autoloader.md).
That means namespaces and class, interface and trait names should correspond to file system paths except root namespace That means namespaces, classes, interfaces and traits must correspond to file system paths and file names accordinly, except for root namespace paths that are defined by an alias.
path that is defined by an alias.
For example, if standard alias `@app` refers to `/var/www/example.com/` then `\app\models\User` will be loaded from For example, if the standard alias `@app` refers to `/var/www/example.com/` then `\app\models\User` will be loaded from `/var/www/example.com/models/User.php`.
`/var/www/example.com/app/models/User.php`.
Custom alias may be added using the following code: Custom aliases may be added using the following code:
```php ```php
Yii::setAlias('@shared', realpath('~/src/shared')); Yii::setAlias('@shared', realpath('~/src/shared'));
``` ```
Additional autoloaders may be registered using standard PHP `spl_autoload_register`. Additional autoloaders may be registered using PHP's standard `spl_autoload_register`.
Helper classes Helper classes
-------------- --------------
Helper class typically contains static methods only and used as follows: Helper classes typically contain static methods only and are used as follows:
```php ```php
use \yii\helpers\Html; use \yii\helpers\Html;