on Wed Apr 04 2012, Sebastian Redl <sebastian.redl-AT-getdesigned.at> wrote:
On 03.04.2012, at 19:20, Dave Abrahams wrote:
on Sun Apr 01 2012, Olivier Grant <olivier.grant-AT-gmail.com> wrote:
Hi Dave,
That's going to be an interesting presentation. Here is a small piece of code that allows to generate a traits structure that determines if a call can be made on an object with a specific function name and specific arguments and return value :
https://gist.github.com/2276393 (compile with : g++ -std=c++0x -Wall -o has_callable has_callable.cpp)
This was not possible in C++03, or at least not completely possible, and the code is much simpler with C++11 for the cases where it was possible as well.
Yep, I see. However, I also have some questions about the utility of such traits. As I mentioned to Mathias, structural matching is always susceptible to false positives. What do you use this for?
I have used something like this to define a generic Set concept (bool contains(const Set& set, const Value& value)). Since in this concept, every normal value represents its own singleton set, I have used is_callable to separate out functions and function-like objects that return bool.
Hm. Can you describe this concept more fully, e.g. with a requirements table or ConceptGCC syntax? -- Dave Abrahams BoostPro Computing http://www.boostpro.com