[Boost-users] Re: B is_convertible to A<T> for some T

From: Tom Widmer (tom_usenet_at_[hidden])
Date: 2005-01-11 06:11:46

Aleksey Gurtovoy wrote:

 > Agoston Bejo writes:
 >
 >> Hello,
 >>
 >> how do I express through template metaprogramming or in a similar
 >> way that a class is convertible to a template class for some T1?
 >> I.e., the condition: "There exists some T1 such that B is
 >> convertible to A<T1>".
 >
 >
 >
 > Use overload resolution. The easiest way would probably be to take
 > 'is_convertible' implementation for your compiler and replace the
 > overload used to detect 'To' type convertibility with with a function
 > temlate accepting 'A<T1>'.

But template argument deduction will fail, won't it, since user defined 
conversions aren't considered when deducing template arguments? 
Obviously, if the class is derived from A<T1> for some T1, then it 
should work, since the derived-to-base conversion is considered.

Tom