I have a class that is getting a huge number of template parameters (mostly a bunch of size_t used for vector sizes).  They have a natural organization into groups, but almost all of them have a default as 0.

How do you suggest that I design the template parameter for this?  Is there any way to use some kind of associative container so I could look these up by "name" and default to 0 if they aren't there?  I can't see how to use mpl::map to do this kind of stuff.

Simplified Pseudocode:

--------------------

What I have:

template<std::size_t IndividualSize = 0, std::size_t AggregateSize> //Many others

class my_problem{...};

What I want:

template<class StateSizes> class MyProblem{...}

Called something like:

typedef my_problem<map<AggregateSize, 2> > my_problem_type;

where AggregateSize is an enum, placeholder struct, etc.  And in this case I would default IndividualSize to 0.

-Jesse