On Thu, Nov 18, 2004 at 02:00:40PM +0000, Daniel James wrote:
I've written a macro (the implementation is attached) for generating a function object for using overloaded functions with generic code such as the STL algorithms and boost::bind. A simple example of it's use: [snip] Any comments on this? Would anyone else find this useful? Also, has anyone done something similar? I'd be surprised if no one has, I always feel like I'm missing something when I'm doing this kind of thing.
Out of curiosity my first thought was to see if I could use std::tolower in std::transform, like so: #include "overloaded.hpp" #include <string> #include <algorithm> #include <cctype> using std::tolower; GENERATE_OVERLOADED(int, tolower); int main() { std::string s("FNORD"); std::transform(s.begin(), s.end(), s.begin(), tolower_overloaded); } (The using declaration is needed to prevent the instance of the generated type being named "std::tolower_overloaded") Unfortunately this fails to compile because there is no nullary form of std::tolower so the nullary overload gives this error: /usr/include/ctype.h: In member function `ResultType GENERATE_DETAIL::tolower_overloaded_t<ResultType>::operator()() const': /usr/include/ctype.h:81: error: too few arguments to function `int tolower(int)' tolower.cc:8: error: at this point in file In fact, I get a similar error for the example code in your mail: overloaded.cc: In member function `ResultType GENERATE_DETAIL::foo_overloaded_t<ResultType>::operator()() const': overloaded.cc:7: error: no matching function for call to `foo()' overloaded.cc:4: note: candidates are: void foo(int) overloaded.cc:5: note: void foo(char*) So although I can see uses for this, I can't use it :-) jon -- "The easy confidence with which I know another man's religion is Folly leads me to suspect that my own is also." - Mark Twain