class_alias() - php 类对象函数
class_alias()
(PHP 5 >= 5.3.0, PHP 7)
为一个类创建别名
说明
class_alias(string $original,string $alias[,bool $autoload=TRUE
]): bool基于用户定义的类$original创建别名$alias。这个别名类和原有的类完全相同。
参数
$original原有的类。
$alias类的别名。
$autoload如果原始类没有加载,是否使用自动加载(autoload)。
返回值
成功时返回TRUE
,或者在失败时返回FALSE
。
范例
Example #1class_alias()例子
以上例程会输出:
bool(true) bool(false) bool(true) bool(true) bool(true) bool(true) bool(true)
参见
get_parent_class()
返回对象或类的父类名is_subclass_of()
如果此对象是该类的子类,则返回 TRUE
class_alias() gives you the ability to do conditional imports. Whereas the following will not work: the following, using class_alias, will: The semantics are slightly different (I'm now indicating that Container extends from an ArrayObject implementation in the same namespace), but the overall idea is the same: conditional imports.
If you defined the class 'original' in a namespace, you will have to specify the namespace(s), too:
class_alias also works for interfaces!
class_alias() creates aliases only for user defined classes, not for classes supplied by PHP (PHP will show the warning "First argument of class_alias() must be a name of user defined class"). To create aliases for every kind of classes, use namespaces:
At first, you might wonder that: is equivalent to: class_alias is NOT equivalent to class extending! Private methods/properties are unseen in child classes, but in alias classes they are.
At first, you might wonder that: is equivalent to: BUT when derivation creates a new class name - that means, you can then instantiate a new kind of objects - aliasing is just what it says: a synonym, so objects instantiated with the aliased name are of the exact same kind of objects instantiated with the non-aliased name. See this code for example:
It also works with Traits! //yes
The alias really is an alias for the existing class. It's not a new class of any kind - whether by inheritance or otherwise; it doesn't just look and behave exactly like the existing class; it really is the same class. Note in the last line there that aliases are just as case-insensitive as "genuine" class names.
Doesn't work with coupled classes when used along with autoloading. For example, in these classes where each class is autoloaded in a separate class file: Foo.php: Bar2.php: Bar.php: When used with an autoloader like this: Results in fatal error: Declaration of Bar2::fx(Bar2 $bar) must be compatible with Foo::fx(Bar $bar) in ~/Bar2.php on line 2
Doesn't work with coupled classes when used along with autoloading. For example, in these classes where each class is autoloaded in a separate class file: Foo.php: Bar2.php: Bar.php: When used with an autoloader like this: Results in fatal error: Declaration of Bar2::fx(Bar2 $bar) must be compatible with Foo::fx(Bar $bar) in ~/Bar2.php on line 2
Something to note, If the $original class has not yet been defined or loaded, the auto loader will be invoked in order to try and load it. If the class for which you are trying to create an alias does not exist, or can not be loaded with the auto loader, you will generate a PHP Warning.
If you need the same function in PHP versionLike class_alias but for functions:
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