I keep hearing people complaining that C++ doesn’t have garbage collection.
I am so sorry for them. Seriously.
C++ has RAII, and I always complain to find no RAII (or a castrated RAII) in Garbage Collected languages.
What advantages could garbage collection offer an experienced C++ developer?
Another tool.
Matt J wrote it quite right in his post (Garbage Collection in C++ — why?): We don’t need C++ features as most of them could be coded in C, and we don’t need C features as most of them could coded in Assembly, etc.. C++ must evolve.
As a developer: I don’t care about GC. I tried both RAII and GC, and I find RAII vastly superior. As said by Greg Rogers in his post (Garbage Collection in C++ — why?), memory leaks are not so terrible (at least in C++, where they are rare if C++ is really used) as to justify GC instead of RAII. GC has non deterministic deallocation/finalization and is just a way to write a code that just don’t care with specific memory choices.
This last sentence is important: It is important to write code that “juste don’t care”. In the same way in C++ RAII we don’t care about ressource freeing because RAII do it for us, or for object initialization because constructor do it for us, it is sometimes important to just code without caring about who is owner of what memory, and what kind pointer (shared, weak, etc.) we need for this or this piece of code. There seems to be a need for GC in C++. (even if I personaly fail to see it)
An example of good GC use in C++
Sometimes, in an app, you have “floating data”. Imagine a tree-like structure of data, but no one is really “owner” of the data (and no one really cares about when exactly it will be destroyed). Multiple objects can use it, and then, discard it. You want it to be freed when no one is using it anymore.
The C++ approach is using a smart pointer. The boost::shared_ptr comes to mind. So each piece of data is owned by its own shared pointer. Cool. The problem is that when each piece of data can refer to another piece of data. You cannot use shared pointers because they are using a reference counter, which won’t support circular references (A points to B, and B points to A). So you must know think a lot about where to use weak pointers (boost::weak_ptr), and when to use shared pointers.
With a GC, you just use the tree structured data.
The downside being that you must not care when the “floating data” will really be destroyed. Only that it will be destroyed.
Conclusion
So in the end, if done properly, and compatible with the current idioms of C++, GC would be a Yet Another Good Tool for C++.
C++ is a multiparadigm language: Adding a GC will perhaps make some C++ fanboys cry because of treason, but in the end, it could be a good idea, and I guess the C++ Standards Comitee won’t let this kind of major feature break the language, so we can trust them to make the necessary work to enable a correct C++ GC that won’t interfere with C++: As always in C++, if you don’t need a feature, don’t use it and it will cost you nothing.