Supporting design by contract in C++

App.9 is an Annotation Preprocessor for C/C++ programs developed in Unix environments. It recognizes assertions that appear as annotations of the source text, written using extended comment indicators. It recognizes three assertion constructs: assume (preconditions), promise (postconditions), return (specifies a constraint on the return value of a function), and a fourth construct, assert, that specifies a constraint on an intermediate state of a function body.