Variable-length stack allocated arrays

[Rainer Deyke]

Andrei Alexandrescu wrote:
> template SuperStack(T) {
>     private T[] buffer;
>     private enum slackfactor = 2.5;
> 
>     T[] getBuffer(size_t n) {
>         buffer.length = buffer.length + n;
>         return buffer[$ - n .. $];
>     }
> 
>     void releaseBuffer(T[] b) {
>         enforce(b is buffer[$ - b.length .. $]);
>         buffer.length = buffer.length - b.length;
>         if (gc.capacity(buffer) > buffer.length * slackfactor) {
>             // Reallocate buffer to allow collection of slack
>             buffer = buffer.dup;
>         }
>     }
> }

Broken design is broken.

SuperStack!int stack;
auto buffer0 = stack.getBuffer(100);
auto buffer1 = stack.getBuffer(10000000); // Reallocates internal array.
stack.releaseBuffer(buffer1);
stack.releaseBuffer(buffer0); // Assertion failure.


-- 
Rainer Deyke - rainerd at eldwood.com