Comments on: Polymorphic clones in modern C++ https://www.fluentcpp.com/2017/09/08/make-polymorphic-copy-modern-cpp/ Jonathan Boccara's blog Tue, 18 Dec 2018 05:53:11 +0000 hourly 1 https://wordpress.org/?v=6.5.3 By: flowing https://www.fluentcpp.com/2017/09/08/make-polymorphic-copy-modern-cpp/#comment-542 Tue, 12 Sep 2017 19:14:00 +0000 https://www.fluentcpp.com/?p=1181#comment-542 In reply to Jonathan Boccara.

Good point, yes. Indeed, I’d say I’d be astonished if co- and contravariance for hierarchies of producers and consumers *couldn’t* be solved by metaclasses. But it would have to be in the standard, so that all use the same basis for common operations on objects, I assume. Whatever, yet another reason why metaclasses would be really a great added value!

]]> By: Jonathan Boccara https://www.fluentcpp.com/2017/09/08/make-polymorphic-copy-modern-cpp/#comment-533 Mon, 11 Sep 2017 08:54:00 +0000 https://www.fluentcpp.com/?p=1181#comment-533 In reply to flowing.

That’s an interesting point. Maybe this could be a usage for metaclasses?

]]> By: flowing https://www.fluentcpp.com/2017/09/08/make-polymorphic-copy-modern-cpp/#comment-532 Sat, 09 Sep 2017 12:57:00 +0000 https://www.fluentcpp.com/?p=1181#comment-532 Great article, thanks so much! This got me thinking, shouldn’t the C++ standard provide some universal interfaces, like clonable, hashable, and comparable, that then all other interfaces and implementations would inherit from? If all interfaces would inherit from those same base interface(s), wouldn’t this solve the polymorphism problem? To me, having to add “cloneThisIF” methods to all my interfaces and to the implementor of multiple interfaces looks more like a hack than a clean solution. Indeed, it makes JVM languages’ obsession with a common base finally look good… 😉

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