.Single ownership and a strong requirement for it to be so.

________________________________
From: Std-Proposals <std-proposals-bounces_at_[hidden]> on behalf of Thiago Macieira via Std-Proposals <std-proposals_at_[hidden]>
Sent: Monday, February 24, 2025 3:22 PM
To: std-proposals_at_[hidden] <std-proposals_at_[hidden]>
Cc: Thiago Macieira <thiago_at_[hidden]>
Subject: Re: [std-proposals] A non-owning but self zeroing smart pointer for single ownership

On Monday, 24 February 2025 03:26:32 Brasilia Standard Time Robin Savonen
Söderholm via Std-Proposals wrote:
> But I am not sure if we are getting any advantage over shared_ptr.

I've been wondering the same: under what conditions would the proposed class
here be used instead of shared_ptr and weak_ptr?

The class proposed here looks like Qt's QPointer (which has been mentioned),
but that has some important differences:
* it requires the pointed object to derive from QObject
* it reports deletion thread-safely, but it doesn't guarantee the object won't
  get deleted on the next instance

QPointer is implemented using *the exact same* mechanism as QWeakReference and
QSharedPointer, except you can't "lock" the object into a QSharedPointer (you
can't prevent destruction). So if this proposed class were also implemented
using the same ref-counted ref-counter structure block, it would be even more
reason to ask why not use std::shared_pointer in the first place.

--
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
  Principal Engineer - Intel DCAI Platform & System Engineering
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