Re: [boost] Looking for thoughts on a new smart pointer: shared_ptr_nonnull

Subject: Re: [boost] Looking for thoughts on a new smart pointer: shared_ptr_nonnull
From: Gavin Lambert (gavinl_at_[hidden])
Date: 2013-10-07 18:43:02

On 10/7/2013 10:48 PM, Quoth Thorsten Ottosen:
> If the idea is to be 100% shared_ptr interface compatible, it may be
> easier just to extend boost::shared_ptr a little:
>
>    typedef boost::shared_ptr<boost::non_nullable<T>> SharedT;

I don't like that.

If you're suggesting using a wrapper type without changing shared_ptr, 
that won't work because the shared_ptr itself could still be empty, so 
you haven't gained anything.

If you're suggesting specialising shared_ptr for that subtype, I don't 
see any benefit in doing this over defining a new pointer type, since 
you have to redefine everything in a specialisation anyway.

And there's undoubtedly some existing templated code that operates on 
boost::shared_ptr<T> that would be confused by this, or at the very 
least not operate efficiently by including tests for null.

> typedef boost::shared_ptr<boost::non_nullable<T>> WeakT;

I assume that was a typo.  (Weak pointers are not especially useful 
without being able to represent null anyway.)