On 04/03/2011 02:29 PM, simendsjo wrote:
D will copy the original content if a slice expands, but is the following 
behavior
implementation specific, or part of the specification?

        auto a = [0,1,2];
        auto b = a[0..2];
        a.length = 2; // is a[3] already marked for collection by the gc?
        assert(a.ptr == b.ptr);
        b.length += 1; // as b cannot reuse it even though noone is using it
        assert(a.ptr == b.ptr); // ooops, fails.. b is reallocated

As I understand it (there is no real spec for D), this is consistent with the often commented design of D slices. People often explain that slices are like views on (implicite or explicit) ordinary arrays. Then, change on either is seen by both, just like references --*except* when change require resizing. Another point of view is that slices somewhat work like copy-on-write: there is no actual copy until one variable value is changed, then only copy happens --expect when change can happen on place.

Denis
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