Smart pointers. When, where and how?

Question

First off, since there are different kinds of smart pointers, I'd like to focus this question on two of them: reference counted intrusive and non-intrusive smart pointers. The question is asked individualy for each pointer type.

I am not really sure how to formulate my question, so here's what I'm not asking: I am not asking why, or when, are smart pointers needed. Neither which type of smart pointer should I use and for what.

Here is what I'm asking, and I hope it's clear enough: When dealing with "smartly-managed" objects, in which contextes should I use which pointer semantics? That is, smart pointer semantics, raw pointer semantics, something else (Such as a reference to a smart pointer)?

It's preety obvious that when I "store" a pointer to an object (object being a reference counted memory entity), such as a global pointer, or as a class member, it should be a smart pointer, so it would claim ownership, but what about other situations?

When I'm passing a pointer as a function argument, should it be a smart-pointer, a raw pointer, a reference to a smart pointer, or maybe something else? What about returned pointers? Local pointers? so on...

Ofcourse, I could use smart pointers everywhere, which is the safest option, but I am feeling that this is really unnecessary and adds overhead.

Answer 1

IMHO, sometimes it's better to do things faster than to have a minor performance improvement. I'm supposing you will do things faster if you always use smart pointers.

My suggestion: Use smart pointers everywhere. Then use a profiler to see if it generates considerable overhead. Where it does, change it :)

Answer 2

I suggest you limit the use of pointers, smart or otherwise, as much as possible. I don't know your background, but many people coming from languages like Java or C# use pointers when they should be really using values and call by reference. Use of pointers in a C++ program should be relatively rare.