StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
text
Body
copied!<p>In my experience, there are three main ownership patterns that crop up. I will call them tree, DAG and graph.</p> <p>The most common is a tree. The parent owns its children, which in turn owns its children and so on. auto_ptr, scoped_ptr, bare pointers and the boost ptr_x classes are what you typically see here. In my opinion, bare pointers should generally be avoided as they convey no ownership semantics at all.</p> <p>The second most common is the DAG. This means you can have shared ownership. The children a parent owns may also be the children of other children the parent owns. The TR1 and boost shared_ptr template is the main actor here. Reference counting is a viable strategy when you have no cycles.</p> <p>The third most common is the full graph. This means that you can have cycles. There are some strategies for breaking those cycles and returning to a DAG at the cost of some possible sources of error. These are generally represented by TR1 or boost's weak_ptr template.</p> <p>The full graph that can't be broken down into a DAG using weak_ptr is a problem that can't easily be solved in C++. The only good handlers are garbage collection schemes. They are also the most general, capable of handling the other two schemes quite well as well. But their generality comes at a cost.</p> <p>In my opinion, you can't overuse the ptr_x container classes or auto_ptr unless you really should be using containers of objects instead of containers of pointers. shared_ptr can be overused. Think carefully about whether or not you really need a DAG.</p> <p>Of course I think people should just be using containers of scope_ptrs instead of the boost ptr_x classes, but that's going to have to wait for C++0x. :-(</p>

Querying!

Guidance

An individual column

Larger individual text columns get their own page to allow for proper reading.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload