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Comment by gowld | Hacker News Reader

How can you write efficient programs without references? And why are references so painful for you anyway?

A C++ reference is basically a pointer that pretends to not be a pointer. If they have any efficiency advantage over const-correct pointers, I've never heard of it (though I'm at best an intermediate C++ programmer).

Points often cited as disadvantages of references include:

- There's nothing that clearly distinguishes them from regular variables at the point of use. They can therefore obscure the fact that you're not passing by value or mutating a local/member variable (particularly if you don't have good IDE support, and good IDE support for C++ is damn hard for some environments/toolchains/targets)

- There is no concept of a null reference, which can create friction with interfaces that use NULL for optional parameters

These points are also often cited as crucial advantages of references. So it goes.

The second is absolutely an advantage of references, and other than having to use (if I'm being honest, legacy and/or bad) interfaces, there is absolutely not a downside in this regard.

The first can be a legitimate complaint, although I find it's rarely an issue in practice.

Contrast with Rust references, which are very much their own type (they more resemble pointers in their behaviour, with explicit dereferencing and address-of needed). As a C++ dev, this took some getting used to! But I never was a fan of how passing-by-reference was invisible at the call site.

References being non-nullable is a huge advantage of references.

If you need the equivalent of a nullable reference, you can just use std::optional<std::reference_wrapper<T>> instead and make the nullability explicit.

If we used std and wanted every type to be 50+ chars long to type, sure. Or we could just use a pointer, which just so happens is a nullable reference.

We have to use pointers for various reasons. Legacy interfaces use them all over the place, so we continue to do so, and they don't really work like pointers at all, so they're horribly inconsistent. Boilerplate things like conditional & partial initialization require jumping through hoops to get working for references. We also have lots of shared & cached objects, so everything needs to be validated anyway, you don't really gain much by knowing a pointer isn't null.

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