On Sun, Dec 6, 2009 at 11:19 AM, Patrick Horgan <phorgan1@gmail.com> wrote:
Frédéric Bron wrote:
I a in favor of implementing type traits to detect comparison and arithmetic operators. What for logical and bitwise operations?
I have no particular use cases in mind, but my prediction is that if you only do the comparison and arithmetic operators, later someone will be saying, "Why didn't he do that logical and bitwise operators? Now I have to implement them myself!"
A use case I came up with recently that might warrant the need for virtually all operators was implementing a scripting system with a limited number of types. script variables were represented by a boost::variant<> templatized on the set of all possible c++ types that mapped to the script types. Some of these types had various operations possible between them (int+float, string+string, etc) and some combinations didn't (string+int, double-string, etc). I wanted to use the static_visitor pattern and have it throw an exception if the operation did not exist between the two. So I wrote functors such as add_variables() and divide_variables() that used enable_if<> and disable_if<> on the operator() to select the appropriate overload for the visitor to invoke. Since this is a scripting language, there were many more operations possible, not just arithmetic. Zach