Re: [boost] Re: Re: Formal review: Optional library

From: Augustus Saunders (infinite_8_monkey_at_[hidden])
Date: 2002-12-16 17:38:02

William Kempf wrote:
>> Some people, mostly _me_, argued that this is not a good idea
>> because code would change meaning if optional<> is replaced
>> by a pointer.
>
>But it's going to change in any event, because optional<> _isn't_ a
pointer.
>
>But in generic code you must follow the semantics of the concept,
>and optional<> isn't useable when a SmartPointer concept is 
>required.  Define the concept well enough, and optional<> becomes 
>useful in generic code.

Hi Will, I really appreciate the comments you've been making on this
topic, so I wanted to ask for a couple more :)

1) Fernando and I briefly went over defining an OptionalValue
concept, of which real pointers, smart pointers, and optional would
model (along with others, I'm sure).  Is this on the right track to
define the concept "well enough?"

2) Presuming three things:
   a) Pointer interface is kept
   b) OptionalValue concept is well defined
   c) deep comparison is kept
would you be at all concerned about optional compiling when misused
in generic code that presumes different semantics for the comparison
operator?  This feels like a booby-trap to me, but I would like to
know your and other people's opinions on this specific point.

Thanks-
Augustus

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