• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
Plethora

Prevent a base class method from being overridden?

10 posts in this topic

Pretty straightforward question.  Say I have a base class and a derived class.  Is it possible to create a function in the base class and explicitly prevent the derived class from overriding it?  I know I can do the opposite (force the derived class to override) with a pure virtual function, but have never heard of a way to do this.

 

It's not purely necessary, seeing as I can just *not* override it, but I prefer to make things explicit where possible.  

 

For context:  Basically I have a Main_Controller class whose job it is primarily to do event handling.  This is all fine and good, but I find in my game I have two fairly distinct user interfaces when it comes to hotkeys.  One is related to the world map, towns, explorable areas, etc.  The other is specific to battles and the battleMap.  So rather than having two distinct event handlers in one class I thought it would be a lot more flexible to create a base Controller class, and then derive Main_Controller and a Battle_Controller from it.  When a battle began I would then pass off control to the Battle_Controller class.

 

However, there are some gui events (game options menu type stuff) I would like to ensure are being handled the same way in each.  It seems the most obvious way is to ensure that both derived classes are using the base class function for handling these particular events.

0

Share this post


Link to post
Share on other sites
Just make the method non-virtual. That doesn't prevent the base class from overriding it entirely, but all references to the base class will call the base class's method.
0

Share this post


Link to post
Share on other sites

Does final work on non-virtual functions?

No, it can only be used on virtual functions. Same goes for override, as in you can only override a parent class' virtual function.

 

Edit:

The final identifier is there to prevent overriding methods. Technically, I think, you would not be overriding a method if it's not virtual.

Edited by Mussi
2

Share this post


Link to post
Share on other sites

That's what I thought, but I wasn't sure. So 'final' wouldn't actually work in the OP's situation, unless the OP wants a virtual function in the base class that can't be overridden / overloaded - which seems to defeat the purpose of it being virtual (seeing that his described inheritance is only one level deep).

 

I must not be understanding the question. laugh.png

0

Share this post


Link to post
Share on other sites

That's what I thought, but I wasn't sure. So 'final' wouldn't actually work in the OP's situation, unless the OP wants a virtual function in the base class that can't be overridden / overloaded - which seems to defeat the purpose of it being virtual (seeing that his described inheritance is only one level deep).

 

I must not be understanding the question. laugh.png

 

Perhaps you can tell me if this is what I want.  :)  I'm not exactly advanced when it comes to certain topics in c++, polymorphism being one of them.  I've just never used it a whole lot and thus its very possible I'm messing up my terminology or something like that.  Here's some quick pseudo-code:

 

 

class Controller

{

     virtual void handleEvents(...) = 0;    //<--------derived classes must handle events but can do so however they wish

     void passOffEventToGui(...);           //<--------gui events must be sent off to the gui handler, want to make sure this exact function is called by all derived classes

};

 

that's not quite how my actual program works but it gets the point across.  So I know how the pure virtual function works for handleEvents(...), but I want to ensure that passOffEventToGui(...) works exactly the same way in all derived classes.  Am I even looking at this in the right way?

0

Share this post


Link to post
Share on other sites

Seems like this thread has gotten overly complicated.  Simple answer, a virtual method is overridable until a derivative creates a final version of said method.  A non virtual method is permanent and you just need to ensure that you expose it correctly with the public access qualifier or that your derivative inherits the protected methods (if said method is protected that is).  In other words your pseudo code is correct as is, the virtual handleEvents will be overrideable the passOffEventToGui will not.  That is the purpose of inheritance, that you can "inherit" the methods of one base class into it's derivatives.  The "virtual" is the special keyword or qualifier if you will that makes a method overrideable.

2

Share this post


Link to post
Share on other sites

Thanks for both the direct answer to my question and the explanation of the concepts.  Both are very helpful.

 

:)

0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0