Several considerations for PHP using static methods _php Tips

This article illustrates several common considerations for using static methods in PHP. Share to everyone for your reference. The specific methods are as follows:

1. even if the method in the class is not declared with static, but it is not used to the variable class member variables, the operator can still be used externally:: To invoke ;

2. The value of the $this in a method invoked in a static manner (by:: operator) is determined by the context in which it is invoked! Not the class that defines him !!

For example, the following code:

<?php 
class TestClass1 
{public 
  $normal _v = ' normal_v from TestClass1 '; 
  public static $STATIC _v = ' static_v from TestClass1 '; 
  Public Function test_func1 () 
  { 
    echo $this->normal_v. ' <br/> '. Self:: $STATIC _v; 
  } 
} 
Class TestClass2 
{public 
  $normal _v = ' normal_v from TestClass2 '; 
  public static $STATIC _v = ' static_v from TestClass2 '; 
  Public Function Test_func2 () 
  { 
    testclass1::test_func1 (); 
  } 
} 
$t 2 = new TestClass2 (); 
$t 2->test_func2 (); 

This code is what the output will be, I thought it would be normal_v from TestClass1 <br/> Static_v from TestClass1, the test found that I was wrong, the correct output is:

Normal_v from TestClass2
Static_v from TestClass1

Description: Test_func1 () Although it is defined in the TestClass1, but is called in the TestClass2, its internal $this variable is determined by the TESTCLASS2!

In fact, the relationship between these two classes should belong to "bidirectional association".

Interested friends can test run this example, I believe there will be a new harvest!