Re: [boost] Re: Boost Array Initialization Technique

From: christopher diggins (cdiggins_at_[hidden])
Date: 2005-06-01 13:07:48

----- Original Message ----- 
From: "Jonathan Wakely" <cow_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Wednesday, June 01, 2005 1:36 PM
Subject: Re: [boost] Re: Boost Array Initialization Technique

> On Wed, Jun 01, 2005 at 01:07:25PM -0400, christopher diggins wrote:
>> I stated that far too strongly, sorry. My reasoning is that the
>> implementation and interface of a numerical array could be optimized 
>> versus
>> a general array. I would not design numerical arrays and general purpose
>> arrays in the same way. For instance I would design a general purpose 
>> array
>> to be default initialized, while I would permit a numerical array to be
>> non-initialized. However, this is all moot because it is now perfectly
>> clear to me that Boost.Array has the mandate to be as much like a 
>> built-in
>
> Actually, it's moot because it's been semi-standardised in TR1, not
> because you now understand the design goals ;)
>
>> array as possible. Even if I do not particularly like that decision 
>> choice
>> it is of course an acceptable choice to make. Making it a 
>> pseudo-container
>> on the other hand is in my opinion a very big mistake.
>
> There are good reasons for that too, see the descriptions of
> Stroustrup's c_array and Austern's block for the basics. It's useful.
> Would you rather have an array type that cannot be used with STL-style
> algorithms, because it doesn't provide iterators?

I don't mind iterators, and I do agree they are useful even in 
non-containers, but I do mind max_size() and empty(). They are there to make 
the container look like an STL container, though it doesn't behave as one. 
This is just plain misleading.

> You've presented one argument against, namely that generic code that
> requires models of the container concept will misbehave when given a
> type that doesn't model the container concept.  That's a simple
> violation of preconditions - which can be statically enforced with
> concept checks.

Good point, but I should point out very little existing code actually uses 
concept checks (at least for the time being, hopefully this will change 
soon). I am concerned that people will assume that max_size() and empty() 
exist to make Boost.Array an STL conformant container, which I think would 
be a very reasonable assumption!

> jon

-Christopher Diggins