Double Colon in PHP:: Usage

A few days ago in Baidu know inside see someone asked PHP double colon:: The use, at that time to his answer is relatively concise because the phone typing is not convenient! It suddenly comes to mind today, so here's a summary of the double colons I've encountered:: What to use in PHP!

one, when static properties and static methods are called

:: The same as the role, but the use of different objects! :: Refers to static methods or properties within a class, and does not need to be instantiated!

Create a class and create a static property of $ A, a static method B, as follows:

class Test {    staticpublic$a;     Static  Public function B () {}}

If you want to call the static property $ A, the following

Test::$a;

Note that a $ symbol is required before a, which is not the same as the symbol!

If you want to call static method B, the following

Test::b ();

Two, when calling a property or method of its own class or parent class

First create a parent class

class Test {    publicfunction  B () {}}

Then create a subclass to inherit the parent class

class extends Test {    publicfunction  cs () {}}

When we need to call method B of the parent class

Parent::b ();

When we need to call our own method CS, there are two ways

Self::cs ();

$this->cs ();

I met is probably the above two cases, if you have encountered any other situation, welcome to Wang Yip Building's personal blog to add ha!

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Double Colon in PHP:: Usage