From: David Abrahams (david.abrahams_at_[hidden])
Date: 2002-01-10 18:40:12
One thing I want which I don't think is in the proposal is the ability to
determine at compile-time whether or not a type is polymorphic.
I am building a runtime representation of the inheritance hierarchy for type
conversion in Boost.Python. For polymorphic types, I need to generate
downcasts. As it stands, the interface is clumsy because the user has to
tell the library whether a given base class is polymorphic.
If a type X is not polymorphic, it is illegal to even write
where typeid(a)==typeid(X), unless Y is a base class of X.
Since it seems highly unlikely that we'll get the compile-time "tell me
whether this expression would be an error" operator, we ought to be
aggressive about pursuing things that help us avoid making errors in the
first place ;-)
David Abrahams, C++ library designer for hire
C++ Booster (http://www.boost.org)
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