Re: [boost] [intrusive_ptr] Constructor not explicit.

From: Peter Dimov (pdimov_at_[hidden])
Date: 2005-07-15 06:57:22

Russell Hind wrote:
> Just wondered why intrusive_ptr(T * p, bool add_ref = true); isn't
> explicit?  The second arg defaults so (using bcc32-5.6.4), an
> intrusive_ptr can be explicitly constructed from a raw ptr.  Is this
> intended when shared_ptr is designed to prevent this?

shared_ptr can only be constructed from a raw pointer that has been freshly 
obtained via 'new T'. Constructing a shared_ptr from an arbitrary raw 
pointer is usually a recipe for disaster.

intrusive_ptr's strength is that it can freely interoperate with raw 
pointers, including those that are already managed by another intrusive_ptr. 
It is much safer to construct an intrusive_ptr from an arbitrary raw 
pointer.