Jeffrey Lee Hellrung, Jr. wrote:

Eric Niebler wrote:

That's an interesting suggestion. (Thinking ...) It requires the ability
to detect the presence or absence of a nested result<> struct template.

Yes.
 

IIRC, this is difficult, and doesn't work on all compilers.

It's not so different from detecting the presence of result_type; hopefully compilers with lambdas and weak decltype are sufficiently sophisticated to handle it.

The fallback could always be predicated on BOOST_MPL_CFG_NO_HAS_XXX_TEMPLATE as well, though I suspect that's defined for all compilers with decltype.
 

Would you be willing to open a trac ticket and attach a patch?

I can put it on the my TODO list :)

 

If you don't have time for this soon, I could probably do this tonight -- if it's not stepping on your toes. . .