John Maddock
I 'm trying to put the implementation into a dll and mark the explicit instantiation of Normal as exported with the following results: 1) With the small_dim_ctor's enabled I get the static assertion when marked for export 2) With the small_dim_ctor's enabled everything is ok when not marked for export 3) With the small_dim_ctor's disabled everything is ok regardless of export marking 4) If I comment out the BOOST_STATIC_ASSERT and build my app with export enabled I can use the resulting dll without any problems
I'm thinking that marking for export is somewhow generating an implicit conversion somewhere but I don't know how.
Unfortunately, when you explicitly instantiate a template every non-template member function gets instantiated, and that triggers the static asserts.
The only workarounds I can see are:
1) Use regular asserts whenever the class is being exported rather than static asserts. 2) Use partial template specialisations for the N = 1, 2 or 3 cases and give them different constructors (no need to static asserts then). 3) Use template constructors instead:
template <class U> explicit Vector( U x ) { BOOST_STATIC_ASSERT(DIM==1); data_[0]=x; }
Hope this helps, John.
I thought I was only marking the explicit specialization of a single method ( eg Normal) for exporting or maybe it's because its not possible to specialize just one method.? After reading your reply I had a look at enable_if but I couldn't figure a way to test the DIM ie template <typename T> explicit Vector( T x, typename boost::enable_if< DIM==1, void*>::type = 0 ) { data_[0]=x; } but I'm not sure I understand how to use it and am still surfing for examples. Thanks for the help. Frank