Re: [boost] Why no non-null smart pointers?

From: Frank Mori Hess (frank.hess_at_[hidden])
Date: 2008-04-03 09:20:09

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On Wednesday 02 April 2008 12:58 pm, Ross MacGregor wrote:
> I just created a very small smart pointer libary for our project. It will
> contain two types of shared pointers: SharedHandle and
> NullableSharedHandle. SharedHandle will be a shared pointer that cannot be
> null by ensuring a non-null construction while NullableSharedHandle will
> basically be a typedef for boost::shared_ptr.

If you're going to make a shared_ptr wrapper that acts like a reference (no 
null, no reset, I assume no assignment) then why not complete the set and add 
another that acts like a value?  That is, one that does deep copies of the 
template type on assignment, and it could also have the non-null requirement.  
It would differ from an ordinary value in that you could obtain shared_ptr 
(or your other wrapper types) from it which share ownership.  It would be 
useful for cases where you currently have a class with a shared_ptr member 
but need to do deep copies of the object owned by the shared_ptr in the 
containing class' assignment/copy constructor.

- -- 
Frank
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