On Mon, 13 Apr 2026 at 13:25, Sebastian Wittmeier via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> And it is still possible to keep the Animal overload beside the new Dog
> and Cat ones. Fulfilling the requirements not to change its code.
>

Exactly. The requirement is just that Cat and Dog do not inherit from
Animal, and that print_name(cat) and print_name(dog) work. That's easy. You
don't need to manually re-implement inheritance or introduce language
support for type erasure.

I hope the interviewer was looking for a simple solution, avoiding
unnecessary overcomplication.




>
>
>
>
>
> -----Ursprüngliche Nachricht-----
> *Von:* Jonathan Wakely via Std-Proposals <std-proposals_at_[hidden]>
> *Gesendet:* Mo 13.04.2026 14:13
> *Betreff:* Re: [std-proposals] Language support for type erasure
> *An:* C++ Proposals <std-proposals_at_[hidden]>;
> *CC:* Jonathan Wakely <cxx_at_[hidden]>;
>
>
> On Fri, 10 Apr 2026, 10:39 Frederick Virchanza Gotham via Std-Proposals, <
> std-proposals_at_[hidden]> wrote:
>
> In a job interview recently I was given the following code:
>
> #include <iostream>
> #include <memory>
> #include <string>
>
> struct Animal {
> virtual ~Animal() = default;
> virtual std::string name() const = 0;
> };
>
> struct Cat : Animal {
> std::string name(void) const override
> {
> return "Cat";
> }
> };
>
> struct Dog : Animal {
> std::string name(void) const override
> {
> return "Dog";
> }
> };
>
> /* DO NOT CHANGE THE CODE BELOW! */
>
> void print_name(Animal const &a)
> {
> std::cout << a.name() << std::endl;
> }
>
> int main(void)
> {
> Cat cat;
> Dog dog;
> print_name(cat);
> print_name(dog);
> }
>
> I was told to remove the inheritance, but I wasn't allowed to edit
> code beneath the indicated line.
>
>
> Or you could just add overloads of print_name taking Cat and Dog which
> works today and is simple to understand. That's the answer I would hope for
> if I asked that question.
>
> No std::function, no allocations, no hanging reference captures, no new
> language features needed. Just clear code.
>
>
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