[Boost-users] (newbie) design question (is there an MPL solution?)

From: Timothy Perrigo (tperrigo_at_[hidden])
Date: 2004-08-09 15:16:37

I'm just now treading into the (rather intimidating) waters of template 
metaprogramming, so I'm not even sure if it will fit what I'm trying to 
accomplish.  I need to create a kind of registry to keep track of 
instances of variables of different types (actually, several of these 
registries, representing different system states); variables of a type 
would be identified by an unique (integer) id.  In other words, the 
variables within a particular registry represent the state of the 
system at a given point in time, so although each registry would have 
variables of the same types and ids, the values of the variables in 
different registries may be different.  If the variables were all of 
the same type, a simple map would work.  What I would like is a way of 
asking this registry for a variable of a specified type and id, and get 
back the appropriate instance (of the appropriate type).  I.e., 
something like the following would be ideal:

MyType mt = registry.get<MyType>(my_id);

Is there anything in the MPL (or elsewhere in Boost) that might help me 
accomplish what I'm looking to do?  If not, does anyone have any design 
suggestions to accomplish this in another way?  Any help would be 
appreciated!

Thanks,
Tim