Re: [boost] Borland Coding Challenge (is_convertible)

From: Mark Rodgers (mark.rodgers_at_[hidden])
Date: 2000-11-22 03:42:23

John,

I don't know if this helps you at all, but I did manage to get your
challenge to compile by changing this line

#define value_test(v, x) checker<(v == x)>::check(v, x, #x);

to this

#define value_test(v, x) \
   enum { BOOST_JOIN(foo, __LINE__) = x }; \
   checker<(v == x)>::check(v, x, #x);
#define BOOST_JOIN( X, Y ) BOOST_DO_JOIN( X, Y )
#define BOOST_DO_JOIN( X, Y ) X##Y

It seems that the usage of is_convertible::value as the value for
an enum forces the compiler to treat it as a compile time constant
henceforth.  Weird!

I don't know if we can do anything about it other than provide 
documentation to this effect so that users can use this workaround.

Mark