Dave Harris wrote:
In-Reply-To: <d80h47$irf$1@sea.gmane.org> technews@kangaroologic.com (Jonathan Turkanis) wrote (abridged):
array can't be given constructors without sacrificing the aggregate initialization syntax.
OK... although I'd rather have constructors than aggregate initialisation syntax. If the problem is performance, surely the compiler can optimise away the difference (given that it's a standard library component with known semantics)?
No, it's not performance -- it's compatibility with built-in arrays. Furthermore, array initializers are considered pretty natural, and the trend is to try to make user-defined types more like arrays in that respect. (See, e.g., http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2003/n1509.pdf; this may not be the most recent paper.)
Anyway, it sounds like this battle is already lost.
Is there a rational for not allowing zero-sized arrays? What is the intended semantics of:
array<int> a; // Or array<int,0>. assert( a.empty() );
Zero sized arrays are allowed, at least by TR1: 6.2.2.4 Zero sized arrays [tr.array.zero] array shall provide support for the special case N == 0. In the case that N == 0, begin() == end() == unique value. Also An instance of array<T, N> stores N elements of type T, so that size() == N is an invariant. This implies that an array has size 0 iff it empty() is true.
? Isn't this kind of thing likely to occur in generic template code?
I don't know. Jonathan