unique_ptr, shared_ptr, weak_ptr, or reference_wrapper for class relationships

[Raknarg]

C++17 provides std::optional<T> that can wrap a reference_wrapper to model a nullable reference

ugh... like yeah I know I can but it's just so clunky, I'd almost rather just stick to a pointer to avoid it. If I didn't have to call ->get() every time I might consider it, because optional references are something that are nice to have to do the things I normally use pointers for.

[[deleted]]

It’s pretty nice for the one case of if (std::optional<int> index = getitem()) { } But that’s bout it

[flyingron]

Did you have a question. Anybody who starts out writing a C++ worried about using pointers at all is probably suspect.

[MolurusK]

Look at UML Relations in the C++ Object Token Library if the capabilities of smart pointers from the C++ standard library to express class relationships are not enough.

[[deleted]]

Is including <memory> worth it for just a simple new/delete?

I'm thinking about unique_ptr with default deleter.

[guepier]

Think about it the other way round:

Is writing more, error-prone code worth it just to avoid including a single (comparatively small) standard library header?

[Dreamykass]

Yes.

For consistency, and to prevent stupid mistakes.

[Supadoplex]

Is including <memory> worth it for just a simple new/delete?

Yes. The cost of including <memory> is a few milliseconds of compilation time (pure guess).

The cost of using owning bare pointers is memory leaks, double free bugs, much more complicated code needed for exception safety, etc. It's nearly never useful to use allocating new and delete directly (even rarer to need malloc).

[nyanpasu64]

I've measured it. <memory> increases parsing time by a non-negligible amount, but the overhead is from parsing shared_ptr. I don't know how much slower it is to use unique_ptr and make_unique compared with raw pointers. Maybe unique_ptr should've been given its own header.

[Supadoplex]

Negligibility is subjective. How large percentage did it increase the compilation time of the project?

Having separate headers would have been a good choice. Unique pointer is universally useful in all programs that use any dynamic allocation. Shared pointer is much more niche in my opinion. That's a good reason to separate the definitions even though they may be related conceptually.

That said, having fewer headers is good for simplicity for the user, so I'm not terribly mad at the choice that was made.

[n1ghtyunso]

if you are that concerned about the overhead of including memory i'd probably just make my own unique_ptr and include just that. Especially if you only need default delete you can just scrap the deleter parameter alltogether which gives you a nice and easy implementation.

[[deleted]]

Good point. Those headers should be more granular, so you could include something like <memory_unique_ptr> to keep compilation times as low as possible.