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
"Andy Little" <andy@servocomm.freeserve.co.uk> wrote 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?
Registering MPL types is a little less trivial than usual, because MPL generates these types. Accordingly, registrations should also be generated, but then we'd run into the problem with the __LINE__ usage. So, I think this should utilize lower-level typeof macros, which do not use __LINE__, but instead allow for Id to be specified directly.
Any mechanism that allows use of Typeof without dependencies on implementation details of other libraries would be appreciated!
I will try to implement such registrations for mpl::vector[n], as an example. However, I think it's ultimately up to the library authors do decide whether or not to make their libraries typeof-enabled (I would be happy to provide any help on the subject). Regards, Arkadiy