So the VTBL would still exist, but for some order od operations (here: Create + someVirtualFunc()) the indirection could/would be optimized out? As the class behind the interface is known from the Create function in this case?   -----Ursprüngliche Nachricht----- Von:Breno Guimarães via Std-Proposals <std-proposals_at_[hidden]> Gesendet:Fr 10.11.2023 02:37 Betreff:Re: [std-proposals] Optimize away VTBL when using single inheritance An:Std-Proposals <std-proposals_at_[hidden]>; CC:Breno Guimarães <brenorg_at_[hidden]>; Hi,  Perhaps this should be directed a compiler vendor then?  Best Regards, Breno G Em qui., 9 de nov. de 2023 22:22, Smith, Jim via Std-Proposals <std-proposals_at_[hidden] <mailto:std-proposals_at_[hidden]> > escreveu: Hi All, Test-driven development (TDD) is my de facto standard for writing software. On some projects I can't use TDD because interfaces introduce VTBL operation into the code. For me this is a serious issue.  I've always used C++ interfaces i.e., classes with all pure virtual functions for TDD, especially when implementing a design patterns like Factory.  I'm proposing a compiler option that will turn a virtual call through an interface, to a direct call on the object. For example,  interface* i = Factory::Create();  i->someVirtualFunc(); In cases where single inheritance is used i->someVirtualFunc() would be optimized to a direct call on the object without any VTBL operation.  This way the TDD code can use the standard VTBL operations, and in production builds a flag can be set to optimize it away. I can't do this myself without mentioning the concrete type created by the factory but the compiler can make the optimization.   --James S.   -- Std-Proposals mailing list Std-Proposals_at_[hidden] <mailto:Std-Proposals_at_[hidden]> https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals -- Std-Proposals mailing list Std-Proposals_at_[hidden] https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals