postmas...@colder.ch wrote:
----- "Nathan Rixham" <nrix...@gmail.com> wrote:
class Point2DManager {
public function distanceBetween( Point2D $p1 , Point2D $p2 ) {};
}
class Point3DManager extends Point2DManager {
public function distanceBetween( Point3D $p1 , Point3D $p2 ) {};
}
This is incorrect. Any class extending Point2DManager should be able to provide
at least as much functionality as the parent class. In other words, it should
not tighten the pre-conditions.
In your case, Point3dmanager will no longer be able to handle 2dpoints, which
is a mistake.
lol, got it - confused myself for a bit there! yes agreed..
incorrect:
class Parent { function equals(Parent $o) {} }
class Child extends Parent { function equals(Child $o) {} }
correct:
class Parent { function equals(Child $o) {} }
class Child extends Parent { function equals(Parent $o) {} }
sorry about the noise,
nathan
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