On Wed, 2008-03-26 at 09:26 -0400, Frank Mori Hess wrote:
does shared_from_this() also guarantee that it never throws?
No, it can throw bad_weak_ptr.
<http://boost.org/libs/smart_ptr/smart_ptr.htm> states that only std::bad_alloc is thrown - if anything is thrown at all. Am I misreading that?
That's talking about the smart pointer classes. shared_from_this is a method of enable_shared_from_this, which isn't a smart pointer.
See last paragraph.
And reading the documentation for weak_ptr, it's not clear to me when a bad_weak_ptr exception is thrown at all. All weak_ptr functions are documented to never throw.
It's thrown by the shared_ptr constructor that takes a weak_ptr argument.
But shared_from_this() requires that there must exist at least one shared_ptr instance that owns the object, which means that the use_count() is always guaranteed to be >0, hence the exception is never thrown by shared_ptr's ctor. Oh, and the ctor of shared_ptr therefore *can* throw something else than std::bad_alloc, right? Unlike shared_from_this(), AFAICS. Regards, Daniel