Re: [Boost-users] intrusive_ptr feature request for constructor

From: Peter Dimov (pdimov_at_[hidden])
Date: 2005-11-13 14:17:27

Bruno Martínez wrote:
> Hi.
>
> intrusive_ptr's constructor takes an bool to signal whether the
> refcount should be initially incremented or not.  The default is true.
>
> I find that the default is different for different types, [...]

No, it shouldn't be. I suspect that you have in mind a type whose initial 
reference count is one instead of zero.

This type is incorrectly designed. Here's why:

T * p = new T;
intrusive_ptr<T> p1( p );
intrusive_ptr<T> p2( p );

Note that, in order to be able to reliably create an intrusive_ptr from a 
raw pointer (a unique selling point for intrusive counting,) the initial 
reference count needs to be zero.