Re: [boost] Re: Array support [was SmartPtr (Loki) - auto_ptr/move c'tor issue]

[Beman Dawes]

At 03:35 AM 2/4/2003, Andrei Alexandrescu wrote:
>"Beman Dawes" <[EMAIL PROTECTED]> wrote in message
>[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
>> * Should a PBSP supply policies that are prone to be used unsafely?
>>
>> I'd say "no" is an acceptable answer, at least for something like the T*
>> conversion in widely used libraries like the Standard Library and Boost.
>>
>> * Should a PBSP allow user supplied policies to modify interface, perhaps
>> in ways that may be unsafe or even just unfortunate?
>>
>> That's tougher. At some point I lose interest in a PBSP if it prevents me
>> from doing the things I want to do, even if I only want to do them in the
>> privacy of my own code.
>
>The original SmartPtr design leaves the onus of choosing the right policy
>combination to the application designer. To me, that's a design I find
>reasonable and in keep with the spirit of C++. Safer designs are possible
>that reject policy combinations that "don't go together" at the price of
>being more complicated or less efficient or less flexible.

Yes, understood.

One of the advantages of a generative approach is the improved ability to reject invalid policy combinations.

In the generative experiments I tried a couple of years ago, there wasn't a problem with added complexity or less efficiency, but the result was definitely less flexible.

A GenVoca or curiously recurring template pattern hierarchy might be able to solve all those problems, but they were at the boundary of my skill level, so I never tried them.

--Beman


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