----- Original Message ----- From: "Jonathan Wakely" <cow@compsoc.man.ac.uk> To: <boost@lists.boost.org> 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