Re: [boost] Loki SmartPtr study: Policy orthogonality issues

From: Andrei Alexandrescu (andrewalex_at_[hidden])
Date: 2002-01-11 02:38:22

> I won't question your decision to not support the *_array versions by
> default since I mostly agree with it.
>
> But don't you think that the smart_ptr power user should be able to make
an
> [] supporting pointer using a policy? (This is a specific instance of a
> general problem: adding features to smart_ptr using a policy.)

That kind of flexibility is a cool thing, though of course it shouldn't be
forgotten that a smart pointer is a smart pointer, not a kitchen sink.

Creating a StoragePolicy that inherits the default StoragePolicy, uses
delete[] and defines operator[] and some arithmetic is easy. The thing is,
you'd want to use CheckingPolicy before you do a dereference. And the
problem raised by Beman comes up: how do you get StoragePolicy's operator[]
use the CheckingPolicy to check the pointer?

The more I think of it, the more sense makes to enable free inter-policy
communication. Would be cool, I think, to find how to do that while still
keep it simple for the users who don't care about that.

Andrei