[boost] Re: Interest in smart pointer with value semantics?

From: Dan W. (danw_at_[hidden])
Date: 2004-01-04 19:21:19

Jim Apple wrote:
> Dan W. wrote:
> 
>> If I said to you, I'll pay you a thousand dollars to keep this phone 
>> book for one night, and make sure it's not altered in any way, and you 
>> agree... Now, next day I come to pick up the phone book and you ask 
>> for the 1G, and I say, "well, you didn't do your job", and you say 
>> "how not? the book is safe!" and then I say "125 people died last 
>> night, that were listed in that phone book, you were to prevent that".

> What if the phone book was only super-secret addresses of gold bricks, 
> say?  Then, owning the phone book is equivalent to owning the bricks.

If you took names at random out of that phone book I entrusted you with 
and phoned people at 2AM just to bother them, robbed them, or firebombed 
their houses, I'd think you a monster, to be sure, but I wouldn't 
specifically accuse you of violating the phone-book safe-keeping 
contract.  Not that I wish to preclude the existance of deeper 
contracts, but the contract as it exists, is not being violated, IMO.

> There's some serious analogy decay here, but the point is, sometimes 
> owning the pointer is equivalent to owning the pointee.
> 
> Maybe it would help everyone if you explianed why that shouldn't happen 
> or isn't applicable here.

Okay, I'm not sure whether by "here" you mean this thread, as it 
unfolds, or value_ptr. Let me say first that I'd welcome AND use (a lot) 
a pointer with ownership and constness propagation as well as deep copy. 
I think it would be a valuable addition. I just don't agree that, not 
having such semantics in existing smart pointers constitutes a violation 
of constness correctness, or that allowing const functions to call 
non-const, non-member functions does;  for that amounts to saying that 
the working definition of const-correctness in the language is 
ill-formed.  For someone to claim that, she'd have to prove that there 
is some self-contradiction in it, which I don't think is the case.