That is, when child.update() is called, should the instance of a derived class implicity call all his superclasses’s update() on itself before?
That is, when child.update() is called, should the instance of a derived class implicity
Share
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
That is, when child.update() is called, should the instance of a derived class implicity call all his superclasses’s update() on itself before?
There’s no good answer (in the languages I know). Sometimes you want to replace the super method. Sometimes you want to slip something in before it executes, and sometimes after. It does seem the extending class needs to know more about the details of the class it’s overriding than it should have to. (This gets awkward with closed-source systems.) Also, the base class really wants to control the behaviour of the calling class sometimes, to force the super method to be called, which isn’t right either. I think the best thing is for the super class to document its overridable methods as best it can so the overriding programmer can guess what to do.
The closest I’ve come to handing this properly and rightly is to make the target method so it cannot be overridden, then have it call a method or methods that do nothing but that can be overridden. Then the overriding class can override whichever methods interest it without being able to undermine the superclass.
The ultimate programming language will have a fool-proof solution to this problem.