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Use self:: or __CLASS__ to make a static reference to the current class, depending on the class in which the current method is defined: using static:: is no longer parsed to the class in which the current method is defined, but is calculated at actual runtime. . It can also be called "static binding" because it can be used for (but is not limited to) calls to static methods.
I was recently asked a small question in the comments of a video: Are there any special considerations when choosing to use static instead of self here? Or we can change the question like this:
What are the specific new static and new self of PHP?
In fact, it should be very clear if we look at an example:
class Father { public static function getSelf() { return new self(); } public static function getStatic() { return new static(); } } class Son extends Father {} echo get_class(Son::getSelf()); // Father echo get_class(Son::getStatic()); // Son echo get_class(Father::getSelf()); // Father echo get_class(Father::getStatic()); // Father
Pay attention to this line hereget_class(Son::getStatic());
The class Son
is returned, which can be summarized as follows:
new self
1.self
returns the class where the keyword new
in new self
is located, such as Here's an example:
public static function getSelf() { return new self(); // new 关键字在 Father 这里 }
always returns Father
.
new static
2.static
Based on the above, it is a little smarter: static
will return to execute new static( )
class, such as Son
execute get_class(Son::getStatic())
returns Son
, Father
execute get_class(Father::getStatic())
returns Father
and in the absence of inheritance, it can be considered that new self
and new static
returns the same result.
Tips: You can use a good IDE to read comments directly. For example, PhpStorm:
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