"Jonathan Turkanis" <technews@kangaroologic.com> wrote in message news:d0iarn$gpf$1@sea.gmane.org...
What about templates with more than one parameter:
template<typename U, typename V> LAZY_OP(Matrix_ + Matrix__<U, V>()); // unprotected comma
Right now I can tell you only one solution: template<typename U, typename V> LAZY_OP((Matrix_ + Matrix__<U, V>())); How do you like it?
Also, I believe Fusion (the sucessor to Tuple) would be a valuable tool. Is it (same as)(old version of) Tuple?
No. (What would be the point, then?) It provides extensible tuple-like Oops. My bad - bad english. sequences, together with a collectin of algorithms and adapters, similar to MPL.
I've not looked at Fusion's algorithms but I'm pretty sure that it won't help me with parsing operators tree and choosing the most conforming lazy operator.
I think it's not documented, but last time I looked at it, the design was close enough to MPL that if you knew MPL and Tuple it would be easy to start using.
The reason I though Fusion would be relevant is that in an expression template library, the information about a complex expression that you need to maintain in order for it to be evaluated once it is complete is:
1. A list of all the concrete objects which particpate in the expression 2. The structure of the expression.
Fusion may provide the infrastructure for this. In the iostreams library, I used something like a homemade tuple; but for a more ambitious implementation of expression templates I would want to use existing tools as much as possible.
I've used in my library home-made template<typename FirstArgT, typename Op, typename SecondArgT> class binary_op; template<typename Op, typename ArgT> class unary_op; template<typename LazyExpr> class result_of; I don't think that Fusion will help me here, but I'll take a look at it. Thanks. -- Pavel Chikulaev