On Sat, 6 Aug 2011, Matt Calabrese wrote:
On Sat, Aug 6, 2011 at 4:38 AM, John Maddock <boost.regex@virgin.net> wrote:
Folks, I have a problem with enable_if: it works just dandy for template member functions in my class, but I have some *non-template* member functions and constructors that I want to enable only if the template is instantiated with template args that meet certain criteria. Seems like I can't do this with enable_if as it then generates an invalid class definition. I guess I could use base classes, and/or partial specialization, but both involve a lot of code duplication I'd rather not have. Anyone any ideas?
Thanks, John.
C++0x has a simple answer to this -- default function template template arguments. This works with constructors and even conversion operators. I added documentation for this kind of usage to trunk back in April or so, but I guess it never made it into Release. A quick example of what you can do in 0x:
Sorry about that -- I probably forgot to check enable_if when I was looking for things to merge. Is the release branch open yet? If so, I'll copy it over ASAP. -- Jeremiah Willcock