Alan Patterson wrote:
Steven Watanabe wrote:
AMDG
Alan Patterson wrote:
Doesn't a += interface make an accumulate interface like:
std::accumulate(data.begin(), data.end(), acc);
more appealing than :
std::for_each(data.begin(), data.end(), acc);
std::accumulate uses result = result + *iter; not result += *iter;
Yes. But I guess the original question was that why not a += (or +) operator implemented in accumulator_set to add samples instead of operator().
The answer to the original question is "because operator+ implies addition".
Using std::accumulate to accumulate samples (in an accumulation library) seems more natural to me than the functional implementation. And, using accumulate implies addition operators.
I respectfully disagree, and "using accumulate implies addition" is one reason. The other is that std::accumulate's interface gives it a very limited usage. std::accumulate accepts a sequence, an initial state and a binary operation. It applies that binary operation on each element and the current state to create a new state. In contrast, an accumulator_set maintains some very complicated and *hidden* internal state. Samples are added one at a time, and the way the internal state is modified cannot be expressed simply or efficiently as a binary operation that accepts the old state and the current sample. Conceptually, an accumulator_set is like std::accumulate's binary function with its state argument bound to it, making it a unary function -- unusable with std::accumulate. Trying to shoe-horn it back into the std::accumulate interface with a too-clever operator overload is simply misguided. -- Eric Niebler BoostPro Computing http://www.boostpro.com