The VXL Project

mundy@... wrote:
> I do wonder about adopting boost smart pointers vs. the existing vxl
> smart pointer.  Is there a big advantage to Boost’s smart pointer? I
> took a very cursory look at the design didn’t seem to be all that
> different.  The main thing seemed to be support for various levels of
> memory sharing.

The primary difference is that the boost shared_ptr is not intrusive.
It does not require the pointed-to type to derive from any object or
have any special member.  All the bookkeeping is kept in a separate
object allocated at initialization from a new raw pointer.  This has
several great advantages, but one drawback is that it is not possible to
construct a new smart pointer to an existing object given only a raw
pointer.  Everyone that shares ownership must have an explicit
shared_ptr to it.  It is not safe to use a raw pointer to such an object
unless it is known that some other place has a smart pointer still
referencing it.

-Brad

mundy@... wrote:
> I do wonder about adopting boost smart pointers vs. the existing vxl
> smart pointer.  Is there a big advantage to Boost’s smart pointer?

There isn't too much that Boost's smart pointer that's different from 
the one in vbl.  In fact, I'm sure that the implementation of 
vbl_shared_ptr was very closely modeled after the Boost one.  Boost does 
provide weak pointers, which are useful in a few cases.  The boost 
implementation is better at handling some corner cases and exotic uses, 
nearly all of which won't affect daily use.

Amitha.