"Larry Evans" <cppljevans@cox-internet.com> wrote in message news:djiene$hps$1@sea.gmane.org...
I'm unfamiliar with polymorphic variants. Could you please give a brief explanation or reference? Is it any way related to the topic discussed here:
http://groups.google.com/group/comp.std.c++/msg/8a90765a6e61ce82
OCaml supports normal varaint types and some called polymorphic types, i'm not sure if i understood them correctly myself but from what i think understand of them is that the set of (possible) types are not closed, allows of for code-reuse etc but i might be wrong. OCaml's definition can be found here: http://caml.inria.fr/pub/docs/manual-ocaml/manual012.html (in the variant types section). "Larry Evans" <cppljevans@cox-internet.com> wrote in message news:djihj1$qnv$1@sea.gmane.org...
On 10/24/2005 04:08 AM, Korcan Hussein wrote: [snip]
I relized this when i was reading Spirit's documentation. I did mention from the begining all terminal leaf node types must be given, like in an MPL
What's a "terminal leaf node type"?
Sorry i couldn't think of a better term/word to use, but basically the types of operands of an overloaded operator (excluding composite type). In the case of Boost.Spirit these would be all the primitive parsers. As Joel de Guzman was saying the problem is Boost.Spirit allows you to add not only new primitive parsers but composite parsers too, it is open to extension.
where Expression is some nonterminal in the grammar. Is Tp what you refer to as a "terminal leaf node type"?
Essentially yes, if this was generalized one way this could work is the user gives a boost.mpl sequence of types of operands (possibly give a sequence types for composite types depending on the context). Unfortunately this doesn't scale to well for Boost.Spirit since new types of either kind could be added later on which requires adding a new type to either type sequence and then recompilation.