On 10/21/2005 04:37 PM, Korcan Hussein wrote:
"Larry Evans" <cppljevans@cox-internet.com> wrote in message [snip]
I'm afraid I don't know what:
type deduction of intermediate results from expression templates
means. Could you explain more with examples?
I'll make a quote from the boost MPL book :-)
[snip] That helps a lot (BTW, it's on p. 236). [snip]
better alternative to type erasor (unless it's already in use or have been discussed about). I think it would be very useful to libraries such as uBlas and Spirit.
[snip]
Boost.Any is one example where type erasing is used, basically you keep richful type info to the very last possible moment and then lose most of it in a polymophic type and use dynamic dispatching etc. So it's like your erasing the type, would you like a code example? ;) No. "type erasure" is in index of the MPL book; so, I'll just consult that.
parse tree of an intermediate expression and create an exact runtime replica of the expression tree using recursive variant types (using Boost.Variant in C++). The creation of the expression tree can be completely automated.
Why would you want a runtime replica? I suppose to solve the "type deduction of intermediate results" problem mentioned above, but, as I've said, I don't know what this is :(
I think that should make a little more sense now, if not i can explain some more if need be ;)
Please do. I'm guessing that the replica is encoded in the variant's which member function. IOW, just like the expression type in: http://www.boost.org/doc/html/variant/tutorial.html#variant.tutorial.recursi... encodes the type of expression as: variant.which() expression type ---------------------------------- 1 int 2 binary_op<add> 3 binary_op<sub> your proposal would do the same for each possible value of expression type. IOW, instead of dynamic dispatching as done by type erasure, the dispatching would be done on variant.which()?