使用include时PHP类路径冲突

Question

I have a problem with including classes. Here's a simple example to explain the problem:

Class no. 1 (path: /home/day/Class_A.php):

class Class_A {
  public function sayHi() {
    echo "Good day";
  }
}

Class no. 2 (path: /home/test/Class_B.php):

class Class_B {
  public function greeting() {
    if(class_exists("Class_A")!=true)
      include "../day/Class_A.php";
    $test = new Class_A();
    $test->sayHi();
  }
}

PHP file (path: /home/php.php)

if(class_exists("Class_B")!=true)
  include "test/Class_B.php";
  $g = new Class_B;
  $g->greeting();

The problem is when php.php includes Class_B and Class_B includes Class_A, Class_B fails to open Class_B because the path of the object of the class is now the same as the php.php file.

My question is: Is there a good and simple way to get around this?

Answer 1

Try changing:

include "../day/Class_A.php";

to

include dirname(__FILE__) . '/../day/Class_A.php';

This way, your include will be relative to the file that is doing the include (Class_B).