My simple review: I spent two hours, read the document once. Looked at constrained.hpp once. The code is well documented, I don't have any technical concerns at first glance. I would like DEBUG sorted out though. Would I typedef all the bounded types? I am not sure, I would rather have an option to disable it using a macro as well. I tried to compile a test program using gcc 4.4 and linux, but I don't have utility/swap.hpp so I gave up. I assume this in a boost beta/sandbox somewhere. Here are my ideas: In my own code, I already have a class called cyclic_iterator that uses the boost iterator facade. It does the same thing as this wrapping iterator does. I have a class called defaulted<typename T, T value>, that will default initialize a value so I don't forget to do it in the constructor. This library reminds me of that. You can combine it if you want. :) Or add something like this: class A { A() { // fails } must_initialize<int> t; }; In OpenGL, they use GLenum for enums, but have a list of #defines with ints, so there is no type checking. I can see when this bounded class would be useful. Checking GL_FROM GL_TO. Constant expression checks: If boost eventually uses c++0x, I'm sure you could do a static_assert with constexpr overloading and have many compile time checks. I definitely think "wrapping iterator" needs to be in boost somewhere, and before I made cyclic_iterator I was surprised it wasn't. wrapping_int is useful. I like effort put into this project, thank you Robert. Overall I would accept it, it's simple and lightweight. Can't be too harmful. Chris