[boost] Typeof and mpl (was Interest in dimension/unit-checking library?)

From: Andy Little (andy_at_[hidden])
Date: 2005-12-21 07:57:18

Hi,

Regarding using Typeof with compile time libraries such as mpl. mpl doesnt 
actually deal in types so when I operate on a mpl vector I might get back a 
mpl::vector7 or something else. Similarly with mpl::math::rational I might get 
back  a mpl::math::rational or a mpl::math::simplified_rational.

 That makes for a very flakey quantities library unfortunately, because in 
compliant mode Typeof is  totally dependent on implementation changes in these 
other libraries, and when the compiler crashes because of unregistered types it 
does so in a huge fashion.

Not sure what if anything can be done about it but I'm wondering whether it is 
worth asking library authors now to provide a mechanism so that user can 
register their libraries types (that would be eg a mpl::vector +++ anything it 
might turn into... is that possible or impractical? )without hassle. That would 
solve my problem I think, but maybe would result in a type registration 
explosion?

Any mechanism that  allows use of Typeof without dependencies on implementation 
details of other libraries would be appreciated!

regards
Andy Little