note 61552 added to function.is-a

Why I test if class A inherit class B or implements interface C before I create class A? <? //That isn't work: //1. function is_A() if(is_A('A','B'))$a=new A; if(is_A('A','C'))$a=new A; //2. operator instanceOf if(A instanceOf B)$a=new A; if(A instanceOf C)$a=new A; ?> ---- Server IP: 212.24.129.6 Probable Submitter: 62.168.30.110 ---- Manual Page -- http://www.php.net/manual/en/function.is-a.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+61552 Delete: added to the manual -- http://master.php.net/manage/user-notes.php?action=delete+61552&report=yes&reason=added+to+the+manual Delete: bad code -- http://master.php.net/manage/user-notes.php?action=delete+61552&report=yes&reason=bad+code Delete: spam -- http://master.php.net/manage/user-notes.php?action=delete+61552&report=yes&reason=spam Delete: useless -- http://master.php.net/manage/user-notes.php?action=delete+61552&report=yes&reason=useless Delete: non-english -- http://master.php.net/manage/user-notes.php?action=delete+61552&report=yes&reason=non-english Delete: already in docs -- http://master.php.net/manage/user-notes.php?action=delete+61552&report=yes&reason=already+in+docs Delete: other reasons -- http://master.php.net/manage/user-notes.php?action=delete+61552&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+61552&report=yes Search -- http://master.php.net/manage/user-notes.php