[Boost-users] shared_ptr in API

From: Philippe Lambert (philippe.lambert_at_[hidden])
Date: 2006-08-02 16:19:35

Hello,

We are a large team of C++ developers, using Boost at large.  We have a
philosophical issue about shared_ptr usage and I'm looking for external
inputs.

The 2 clans are opposed about a simple question:  "Should we use shared_ptr
in the API function signatures of a module (dll or else)".  Both clan use a
lot of Sutter/Meyers/other gurus and authors citation to support their view.

1- Pros:  shared_ptr are everywhere in the current code.  It is the best way
to prevent resources leaks, it is easy to use, convenient, it is mostly
safe.  A lot of gurus are saying "use shared_ptr".  Preventing them in API
will means a lot of .get() in the existing code.

2- Cons:  A shared_ptr in the API give the right to the called function to
keep a copy (virtually permanently) of the object.  It is a bad indication
in the contract if the function doesn't need to keep a copy.  It tell to the
user "take care, I may keep a copy of this and influence his life cycle".
If it is not the case, you should tell it in the signature by asking for a
const reference or something like it.  Also, if the caller have a stack
object and want to use an API function which ask for a shared_ptr, he will
need to create a copy, or create a shared_ptr with a deactivated
destructor...  It is not a beautiful thing, both ways.

Of course, I thing that the correct solution is in between, but how to state
it?

If it is a real issue, I would like to read other team opinion, standard,
decision algo or policy...   If we are technically totally disoriented, I
would like to be redirected...

Thanks to all

Philippe Lambert