Defining < for STL sort algorithm - operator overload, functor or standalone function?

Question

I have a stl::list containing Widget class objects. They need to be sorted according to two members in the Widget class.

For the sorting to work, a less-than compara

Answer 1

For most purposes, a. and b. are the same. So the real question is, when to use a/b and when to use c.

The answer is: use a or b if "less than" makes sense for your object in unequivocal terms. If your class is a number, use <.

If "less than" makes no sense in the context of your class, then please don't overload "operator<" for your class. It will confuse users. Use c. instead, and either make it a nested class or typedef it inside your class so you can write it as Widget::Compare.