D. Dante Lorenso wrote:
All,
I get a fatal error when trying to create a new instance of a derived
class from within a static member which exists in the parent base
class. I think the problem is related to using this call:
new self();
Because the 'self' refers to the parent object and not the derived
class. See the code below and the error message which follows:
---------- 8< -------------------- 8< -------------------- 8< ----------
<?php
// defines base functions and requires derived class to replace foo()
class A {
protected abstract function foo();
public static function bar() {
$x = new self();
$x->foo();
}
}
// defines foo() as it should, but base class doesn't know foo exists
// when it references self()
class B extends A {
protected function foo() {
echo "hello world";
}
}
// show how broken things are
B :: bar();
?>
---------- 8< -------------------- 8< -------------------- 8< ----------
PHP Fatal error: Class A contains 1 abstract method and must therefore
be declared abstract or implement the remaining methods (A::foo) in
.../demo.php on line 9
This gives the problem away..
http://www.php.net/manual/en/language.oop5.abstract.php
Any class that contains at least one abstract method must also be abstract.
Make 'A' abstract:
abstract class A
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