Re: [Boost-users] Library Interface Design

David Abrahams wrote:

Brian Allison writes:

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David Abrahams wrote:

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"Peter Dimov" writes:

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No, a singular iterator is not a valid object and it fulfills no invariants.

That's arguable. From my POV, if it's in a state that a legal program can create, it's within the invariant by definition.

Then (if I read you correctly) even undefined behavior is within the invariant?

No, invariants are about state and UB is about behavior. Behaviors don't fall inside or outside of states.

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Or have I been misunderstanding that legal programs can cause UB?

I don't understand the question, sorry.

When a program causes undefined behavior, that falls into the category I'm calling "illegal program." I don't just mean those programs that can be diagnosed as illegal by the compiler.

I misunderstood you - I thought you meant "illegal program" in the sense of any program which run afoul of the standard. Thanks for the clarification.