Rationales

Interface

• Why did you do X in the interface?
• Then why didn't you follow those exactly?

Copy-on-Write

• Why use copy-on-write? I've heard that causes problems with multi-threaded code.
• Why are you using a roll-your-own system instead of boost::shared_ptr for the copy-on-write stuff?

Not-a-Number and The nothrow_integer Type

• Why have a Not-a-Number value?
• What's with the nothrow_integer type?
• Why have a nothrow_integer type at all?
• Since you've got Not-a-Number, what about negative zero, and positive and negative infinity, like IEEE floating-point numbers?

Random generator

• Why did you implement your own random number generator? You should use Boost.Random instead.
• But why have an insecure random number generator as the default? Why not default to the secure one?

Miscellaneous

• exceptions::too_big sounds like std::range_error to me.
• Why didn't you provide conversions to and from float/double types?
• I've got a great idea! Why don't you do X?