#19376 [Opn]: Class inheritance problem

ID: 19376 User updated by: shamim@poetryunlimited.com Reported By: shamim@poetryunlimited.com Status: Open Bug Type: Scripting Engine problem Operating System: Linux/Windows NT 4 PHP Version: 4.2.2 New Comment: when an object of type test3 calls test3::showMe is the only time this chain should function as displayed, I believe. Thanks. Previous Comments: ------------------------------------------------------------------------ [2002-09-12 13:05:53] shamim@poetryunlimited.com Should I be able to do the following? In the example below, class test1 is a base class for test2 which is a base class for test3. In an object of type test1, if I call the class method test3::showMe, I would expect the class method test3::showMe would be called. This class method (not member function) would would have no class context ($this), since objects of type test1 do not have a member function test3::showMe. This call should therefore fail at the debug call. Instead, the call traverses up to test3, and the recursive parent::showMe calls reverse the traversal back to the class test1, even though class test1 has no knowledge of class test3 or class test2. Or so it should be. And for some reason the $this variable exists at every level. Even though objects of type test1 do not have any test3 or test2 object contexts. I think the polymorphism is broken. Thanks. Code follows. =========================================================== <?php Header("Content-Control: no-cache"); Header("Pragma: no-cache"); function debug(&$obj,$msg) { echo "$msg<br><pre>";var_dump($obj);echo "</pre><hr>\n"; } class test1 { var $a; function test1() {$this->a=0;debug($this,"test1->new");} function setA() {$this->a+=1;debug($this,"test1->setA");} function display() {debug($this,"test1->display");echo $this->a."<br>\n";} function callMe() {debug($this,"test1->callMe");test3::showMe();} function showMe() {debug($this,"test1->showMe");$this->display();} } class test2 extends test1 { function test2() {debug($this,"test2->new");$p=get_parent_class($this);parent::$p();} function display() {debug($this,"test2->display");parent::display();} function showMe() {debug($this,"test2->showMe");parent::showMe();} } class test3 extends test2 { function test3() {debug($this,"test3->new");$p=get_parent_class($this);parent::$p();} function display() {debug($this,"test3->display");parent::display();} function showMe() {debug($this,"test3->showMe");parent::showMe();} } $b=new test2(); $b->setA(); $c=new test1(); $c->setA(); $a=new test1(); $a->showMe(); $a->callMe(); $a->setA(); $a->showMe(); $a->callMe(); $a->setA(); $a->showMe(); $a->callMe(); $a=new test2; $a->showMe(); $a->callMe(); $a->setA(); $a->showMe(); $a->callMe(); $a->setA(); $a->showMe(); $a->callMe(); /* Results: test2->new object(test2)(1) { ["a"]=> NULL } -------------------------------------------------------------------------------- test1->new object(test2)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test1->setA object(test2)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test1->new object(test1)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test1->setA object(test1)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test1->new object(test1)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test1->showMe object(test1)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test1->display object(test1)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- 0 test1->callMe object(test1)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test3->showMe object(test1)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test2->showMe object(test1)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test1->showMe object(test1)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test1->display object(test1)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- 0 test1->setA object(test1)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test1->showMe object(test1)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test1->display object(test1)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- 1 test1->callMe object(test1)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test3->showMe object(test1)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test2->showMe object(test1)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test1->showMe object(test1)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test1->display object(test1)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- 1 test1->setA object(test1)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- test1->showMe object(test1)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- test1->display object(test1)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- 2 test1->callMe object(test1)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- test3->showMe object(test1)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- test2->showMe object(test1)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- test1->showMe object(test1)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- test1->display object(test1)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- 2 test2->new object(test2)(1) { ["a"]=> NULL } -------------------------------------------------------------------------------- test1->new object(test2)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test2->showMe object(test2)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test1->showMe object(test2)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test2->display object(test2)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test1->display object(test2)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- 0 test1->callMe object(test2)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test3->showMe object(test2)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test2->showMe object(test2)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test1->showMe object(test2)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test2->display object(test2)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- test1->display object(test2)(1) { ["a"]=> int(0) } -------------------------------------------------------------------------------- 0 test1->setA object(test2)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test2->showMe object(test2)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test1->showMe object(test2)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test2->display object(test2)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test1->display object(test2)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- 1 test1->callMe object(test2)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test3->showMe object(test2)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test2->showMe object(test2)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test1->showMe object(test2)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test2->display object(test2)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- test1->display object(test2)(1) { ["a"]=> int(1) } -------------------------------------------------------------------------------- 1 test1->setA object(test2)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- test2->showMe object(test2)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- test1->showMe object(test2)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- test2->display object(test2)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- test1->display object(test2)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- 2 test1->callMe object(test2)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- test3->showMe object(test2)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- test2->showMe object(test2)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- test1->showMe object(test2)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- test2->display object(test2)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- test1->display object(test2)(1) { ["a"]=> int(2) } -------------------------------------------------------------------------------- */ ?> ------------------------------------------------------------------------ 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