When I program 'on the fly' I either have the diagram in my head, or I'm working 'linguistically' such that things are correct-by-construction / facts about obj

When I program 'on the fly' I either have the diagram in my head, or I'm working 'linguistically' such that things are correct-by-construction / facts about objects are true because-of-what-they-are rather than because of what they do. For example, using std::shared_ptr to manage a resource instead of trying to reason out all the cases to manually free the resource. I guess what I'm saying is that rather than thinking about all the cases to see that the code does work, I try to write code in a way that it is not possible that it does not work.