Re: [Boost-users] [tuple] Tuple arithmetic

Bill Buklis writes:

Is there any facility to perform arithmetic operations on a tuple?

For example:

struct data { double a, b; };

data d1 = {1.0, 2.0}; data d2 = {2.5, 5.5};

// These two lines are not valid, but simulate what I want. boost::tie(d1.a, d1.b) *= 10.0; // Multiply each element by 10.0 boost::tie(d1.a, d1.b) += boost::tie(d2.a, d2.b); // Add the elements from the second object

After calculations, d1 should equal {12.5, 25.5};

Using a tuple this way is probably not the best idea. Tuples are intended for heterogeneous types. If all you really want is a fixed length container for doubles you should use boost/std::array<double>. If you really insist on the tuple, here is tuple_for_each isn't that hard: template inline void for_each(boost::tuples::cons const& tuple, F f) { f(tuple.get_head()); } template inline void for_each(boost::tuples::cons const& tuple, F f) { f(tuple.get_head()); for_each(tuple.get_tail(), f); } double a, b; for_each(tie(a,b), [](double& x) { x *= 10.0; }) HTH, Philipp Moeller