On Thu, Jun 10, 2010 at 3:39 PM, Chad Nelson <chad.thecomfychair@gmail.com> wrote:
On 06/10/2010 10:15 AM, Jeffrey Lee Hellrung, Jr. wrote:
I've tried making the algorithms independent by having them take an array and other information, but they need the freedom to reallocate as necessary (or I'd have to have two functions for each operation). That means passing them the allocator as well, at the very least. You end up
Why do you need to pass the allocator? You cannot put the responsibility on the client code to provide a pointer to a free chunk of memory (whether heap/free store-allocated or stack-allocated) to write to?
I could, but I don't see the point. See below.
The alternative, you say, is "I'd have to have two functions for each operations". Can you elaborate?
One to calculate how much memory would be needed, and (probably) allocate it -- the calculation is different for every operation. The other to do the actual calculation.
I do not buy this: as an example, std::copy does not need to know the size of the output sequence nor need to know how to grow it (one can for example use back_inserter for automatic growth). Couldn't xint use a similar strategy? For an heap allocated big int the ouptut iterator can take care of any reallocation, while for a fixed point big int, in case of overflow, one could chose between UB, assert or throw. In principle there is no reason for algorithms to deal with memory allocation details. -- gpd