Approximation with available language and pre-processor

Question

What are the Approximation with available language and pre-processor features?

Answer 1

Since there is no language support for PbC in mainstream languages such as C++, this has to be modeled. Modeling PbC capabilities using existing language features avoids specific language and compiler issues, but can require significantly increased design and programming effort, especially when used with object-oriented programming language class hierarchies. The approach has an increased probability of introducing errors or inconsistencies in the contract implementation itself. The major issue for pre- and post-conditions is inheritance.In order to preserve semantics, a pre-condition in an overriding method should always be equal to or weaker (accept more) than the overridden method, and a post-condition should always be equal to or stronger (ensure more) than the overridden method.

For example: