In-depth learning of Yii2--yiibaseObject class, yii2--yii_PHP tutorial

In-depth learning of Yii2--yiibaseObject class, yii2--yii

We said before that most classes in Yii2 inherit from yiibaseObject, let us take a look at this today kind.

Object is a basic class that implements the function of attributes. Its basic content is as follows:

<?<span>php
namespace yii\base;

</span><span>use</span><span> Yii;

</span><span>/*</span><span>*
 * Object 是一个基础类，实现了属性的功能
 * Yii最基础的类，大多数类都继承了该类
 </span><span>*/</span>
<span>class</span> <span>Object</span> <span>implements</span><span> Configurable
{
    </span><span>/*</span><span>*
     * 获取静态方法调用的类名。返回类的名称，如果不是在类中调用则返回 FALSE。
     </span><span>*/</span>
    <span>public</span> <span>static</span> <span>function</span><span> className()
    {
        </span>...<span>
    }

    </span><span>/*</span><span>*
     * Constructor.
     </span><span>*/</span>
    <span>public</span> <span>function</span> __construct(<span>$config</span> =<span> [])
    {
        </span>...<span>
    }

    </span><span>/*</span><span>*
     * 初始化对象
     </span><span>*/</span>
    <span>public</span> <span>function</span><span> init()
    {
    }

    </span><span>/*</span><span>*
     * 魔术方法，实现 getter
     </span><span>*/</span>
    <span>public</span> <span>function</span> __get(<span>$name</span><span>)
    {
        </span>...<span>
    }

    </span><span>/*</span><span>*
     * 魔术方法，实现 setter
     </span><span>*/</span>
    <span>public</span> <span>function</span> __set(<span>$name</span>, <span>$value</span><span>)
    {
        </span>...<span>
    }

    </span><span>/*</span><span>*
     * 魔术方法，实现 isset，基于 getter 实现，有 getter 方法的属性才算存在
     </span><span>*/</span>
    <span>public</span> <span>function</span> __isset(<span>$name</span><span>)
    {
        </span>...<span>
    }

    </span><span>/*</span><span>*
     * 魔术方法，实现 unset，基于 setter 实现，有 setter 方法的属性才能 unset 掉
     </span><span>*/</span>
    <span>public</span> <span>function</span> __unset(<span>$name</span><span>)
    {
        </span>...<span>
    }

    </span><span>/*</span><span>*
     * Calls the named method which is not a class method.
     </span><span>*/</span>
    <span>public</span> <span>function</span> __call(<span>$name</span>, <span>$params</span><span>)
    {
        </span>...<span>
    }

    </span><span>/*</span><span>*
     * 检查对象或类是否具有 $name 属性，如果 $checkVars 为 true，则不局限于是否有 getter/setter
     </span><span>*/</span>
    <span>public</span> <span>function</span> hasProperty(<span>$name</span>, <span>$checkVars</span> = <span>true</span><span>)
    {
        </span>...<span>
    }

    </span><span>/*</span><span>*
     * 检查对象或类是否能够获取 $name 属性，如果 $checkVars 为 true，则不局限于是否有 getter
     </span><span>*/</span>
    <span>public</span> <span>function</span> canGetProperty(<span>$name</span>, <span>$checkVars</span> = <span>true</span><span>)
    {
        </span>...<span>
    }

    </span><span>/*</span><span>*
     * 检查对象或类是否能够设置 $name 属性，如果 $checkVars 为 true，则不局限于是否有 setter
     </span><span>*/</span>
    <span>public</span> <span>function</span> canSetProperty(<span>$name</span>, <span>$checkVars</span> = <span>true</span><span>)
    {
        </span>...<span>
    }

    </span><span>/*</span><span>*
     * 检查对象或类是否具有 $name 方法
     </span><span>*/</span>
    <span>public</span> <span>function</span> hasMethod(<span>$name</span><span>)
    {
        </span>...<span>
    }
}</span>

If you want to see detailed annotations, you can visit https://github.com/ReadCode/yii2-2.0.3-annotated/blob/master/framework/base/Object.php

From the above content, we can see that the Object class overrides the __get and __set methods. Let’s take a closer look at these two methods:

    <span>/*</span><span>*
     * Returns the value of an object property.
     *
     * Do not call this method directly as it is a PHP magic method that
     * will be implicitly called when executing `$value = $object->property;`.
     *
     * 魔术方法，实现 getter
     *
     * @param string $name the property name
     * @return mixed the property value
     * @throws UnknownPropertyException if the property is not defined
     * @throws InvalidCallException if the property is write-only
     * @see __set()
     </span><span>*/</span>
    <span>public</span> <span>function</span> __get(<span>$name</span><span>)
    {
        </span><span>$getter</span> = 'get' . <span>$name</span><span>;
        </span><span>if</span> (<span>method_exists</span>(<span>$this</span>, <span>$getter</span><span>)) {
            </span><span>//</span><span> 对象存在 $getter 方法，就直接调用</span>
            <span>return</span> <span>$this</span>-><span>$getter</span><span>();
        } </span><span>elseif</span> (<span>method_exists</span>(<span>$this</span>, 'set' . <span>$name</span><span>)) {
            </span><span>//</span><span> 如果存在 'set' . $name 方法，就认为该属性是只写的</span>
            <span>throw</span> <span>new</span> InvalidCallException('Getting write-only property: ' . <span>get_class</span>(<span>$this</span>) . '::' . <span>$name</span><span>);
        } </span><span>else</span><span> {
            </span><span>//</span><span> 否则认为该属性不存在</span>
            <span>throw</span> <span>new</span> UnknownPropertyException('Getting unknown property: ' . <span>get_class</span>(<span>$this</span>) . '::' . <span>$name</span><span>);
        }
    }

    </span><span>/*</span><span>*
     * Sets value of an object property.
     *
     * Do not call this method directly as it is a PHP magic method that
     * will be implicitly called when executing `$object->property = $value;`.
     *
     * 魔术方法，实现 setter
     *
     * @param string $name the property name or the event name
     * @param mixed $value the property value
     * @throws UnknownPropertyException if the property is not defined
     * @throws InvalidCallException if the property is read-only
     * @see __get()
     </span><span>*/</span>
    <span>public</span> <span>function</span> __set(<span>$name</span>, <span>$value</span><span>)
    {
        </span><span>$setter</span> = 'set' . <span>$name</span><span>;
        </span><span>if</span> (<span>method_exists</span>(<span>$this</span>, <span>$setter</span><span>)) {
            </span><span>//</span><span> 对象存在 $setter 方法，就直接调用</span>
            <span>$this</span>-><span>$setter</span>(<span>$value</span><span>);
        } </span><span>elseif</span> (<span>method_exists</span>(<span>$this</span>, 'get' . <span>$name</span><span>)) {
            </span><span>//</span><span> 如果存在 'get' . $name 方法，就认为该属性是只读的</span>
            <span>throw</span> <span>new</span> InvalidCallException('Setting read-only property: ' . <span>get_class</span>(<span>$this</span>) . '::' . <span>$name</span><span>);
        } </span><span>else</span><span> {
            </span><span>//</span><span> 否则认为该属性不存在</span>
            <span>throw</span> <span>new</span> UnknownPropertyException('Setting unknown property: ' . <span>get_class</span>(<span>$this</span>) . '::' . <span>$name</span><span>);
        }
    }</span>

Based on the above code, we can see that if you access a certain property of an Object object, Yii will call a function named get property name() . For example, SomeObject->Foo will automatically call SomeObject->getFoo(). If a property is modified, the corresponding setter function will be called. For example, SomeObject->Foo = $someValue will automatically call SomeObject->setFoo( $someValue) .

Take SomeObject's Foo as an example. If only the getFoo() method exists, then it is read-only. If only the setFoo() method exists, then it is write-only. Only when both methods exist Both readable and writable.

One thing to note is that only when reading and writing a non-existent member variable of an object, __get() __set() will be called automatically. If Foo is a public property, it will not go through the __get() and __set() methods.

So usually attributes are private, for example:

<span>class</span> User <span>extends</span> yii\base\<span>Object</span><span>
{
    </span><span>private</span> <span>$_name</span><span>;

    </span><span>public</span> <span>function</span><span> getName()
    {
        </span><span>return</span> <span>$this</span>-><span>_name;
    }

    </span><span>public</span> <span>function</span> setName(<span>$name</span><span>)
    {
        </span><span>$this</span>->_name = <span>trim</span>(<span>$name</span><span>);
    }
}</span>

We can also do some special processing in the get and set methods.

In addition to __get() __set(), yiibaseObject The following methods are also provided to facilitate the use of attributes:

• __isset() is used to test whether the attribute value is not null , in isset($ object->property) is automatically called. Note that this property must have a corresponding getter.
• __unset() is used to set the attribute value to null in unset($object ->property) is automatically called. Note that this property must have a corresponding setter.
• hasProperty() is used to test whether there is a certain property. That is, a getter or setter is defined. If the parameters of hasProperty() $checkVars = true (default is true ), then as long as the member variable with the same name is also considered to have this attribute, as mentioned earlier public $title .
• canGetProperty() Tests whether a property is readable. The meaning of the parameter $checkVars is the same as above. As long as the getter is defined, the property is readable. At the same time, if $checkVars is true . Then as long as the class defines member variables, whether they are public, private or protected, they are considered readable.
• canSetProperty() tests whether a property is writable. The parameter $checkVars has the same meaning as above. As long as the setter is defined, the property can be written. At the same time, in $checkVars is ture . Then as long as the class defines member variables, whether they are public, private or protected, they are considered writable.

Students who are interested in the Yii2 source code can pay attention to the project yii2-2.0.3-annotated. A lot of comments about the Yii2 source code have been added to it, and they will continue to be added in the future~

Interested students can also participate and submit comments on the Yii2 source code.

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