Re: [boost] [afio] Formal review of Boost.AFIO

Subject: Re: [boost] [afio] Formal review of Boost.AFIO
From: Niall Douglas (s_sourceforge_at_[hidden])
Date: 2015-08-31 10:52:11

On 31 Aug 2015 at 2:27, Gruenke,Matt wrote:

> > You lose the possibility to express your intent. There is no conceptual
> > need in having shared ownership.
> 
> I agree with this.  Libraries shouldn't dictate memory management
> strategies to their users.  If you must accept only shared_future<> as
> preconditions, that's understandable.  But it doesn't mean you need to
> return them, when they're not (yet) shared by anything. 
> 
> This semantic distinction can have real, practical implications.  When I
> see code using shared_ptr<>, it's a sign to me that the object is truly
> shared.  This has implications on how I use it, so I need to take the
> time to understand with whom it's shared and how they access it.  If
> it's not *really* shared, then it's misleading and potentially wastes
> users' time. 

I don't know why you and the HPC crowd are conflating shared_ptr with 
shared ownership. It an atomic safe reference counting implementation 
which provides no guarantees to its pointee.

I find it personally unfortunate that C++ decided to call it 
shared_ptr because of the word "shared" in the name, because it 
really isn't what its name says.

I might add that in AFIO I use the typedef handle_ptr. You don't 
think to think shared anything, just use afio::handle_ptr and stop 
worrying about shared_ptr. It's an implementation detail, and not 
important.

> Another reason why it might be necessary to understand the ownership
> structure of shared objects is a consequence of the fact that ref
> counting != garbage collection.  Since it's incumbent on the user to
> avoid circular references, this is also a cost, in development time. 

I think you are making up speculative problems here. This has never 
been an issue in anything I've written using AFIO to date, and I 
would doubt it ever will.

Niall

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