[moron4hire]

I had a similar feeling. As a long-time C# programmer (how old is C#? That many years), I look at this and get really wide-eyed, "how is that at all a good idea?!"

A lot of these features seem like ways to hack around the fact that C++ templates are not generics, they are literally templates for writing copies of classes. It seems like features like this are going to make code size explode.

A lot of the examples also seem very smelly from an OOP perspective. We should one class be able to have different fields depending on template parameters? That seems like something one should do in a subclass.

[adrianN]

I'm not sure what you mean by generics if you think that C++ templates are not a kind of generics. Do you prefer that everything happens at runtime?

Similarly, subclasses as opposed to templates carry a runtime cost. Virtual function calls are not free. Why pay that cost if you can deduce the right code from the types at compiletime? Besides, and this is probably a matter of opinion, I find code hard to follow that uses inheritance heavily.

[Retra]

By "generics", I presume they mean template parameters which are checked at declaration, not at use.

[mattnewport]

That sounds like concepts, as used extensively in the OP.

[steveklabnik]

One significant difference with concepts is that they are optional.

[mattnewport]

Gradual typing is mostly a good thing for metaprogramming I think. Even if it was just a compromise for backwards compatibility I'd still take it over C#'s rather limited generics.

[steveklabnik]

I think C# is a good language, but I also am not sure that it's a poster child for this particular language feature. (I mean this literally; I don’t have enough experience to really know how it compares to the usual suspects in this area.)

[seanmcdirmid]

C++ supports generic through template/macro expansion, rather than through parametric polymorphism.

[mattnewport]

I'm very familiar with C++ and C# and overall I find I like C++ a lot better. There are a few nice convenience features of C# but knowing both languages I tend to find whenever they differ I feel like C++ made the better design choice.

And C# going all in on OOP is a part of that. It's reasonably clear now that OOP was mostly a big mistake and a dead end. C++ is less infected by going all in on it as it has always been a multi paradigm language.