generalization

I understand that abstraction is about taking something more concrete and making it more abstract. That something may be either a data structure or a procedure. For example: Data abstraction: A rectangle is an abstraction of a square. It concentrates on the fact a square has two pairs of opposite sides and it ignores the fact that adjacent sides of a square are equal. Procedural abstraction: The higher order function map is an abstraction of a procedure which performs some set of operations on a list of values to produce an entirely new list of values. It concentrates on the fact that the

I am pretty new to UML, so I have some questions about Generalization and Realization. I am modeling the behavior of an electronic microcontroller and I need to generate C++ code from the UML description. As far as I know, a class realizes an interface, that means it may provide the implementation of an interface. A generalization relationship may exist between two classes. In that case the derived class inherits all the members of the base class and gains access to public and protected members. Here is my question (I am using Visual Paradigm as modeling tool). Let us assume we have a module

"There are only two hard problems in Computer Science: cache invalidation and naming things." Phil Karlton Is there a general solution or method to invalidating a cache; to know when an entry is stale, so you are guaranteed to always get fresh data? For example, consider a function getData() that gets data from a file. It caches it based on the last modified time of the file, which it checks every time it's called. Then you add a second function transformData() which transforms the data, and caches its result for next time the function is called. It has no knowledge of the file - how do you