Hello all, Below I am comparing DBC features between this C++ library, Eiffel, the D programming language, and the C++ Standard Committee proposal for adding DBC to C++ [Ott04]. Does anyone know of other libraries offering Eiffel-like DBC support for C++? As far as I know, there is no publicly available library for C++ that supports all DBC features offered by Effiel. Existing DBC tools for C++ lack of support for either "old" in postconditions, subcontracting, automatic contract documentation, or a combination of the above. This library provides all Eiffel DBC features for C++ (and it does not require external preprocessing tools, just the C++ preprocessor). Thank you. Lorenzo DBC FEATURE COMPARISON [Ott04] ["C++ Std. Prop." below] T. Ottosen, Proposal to add Design by Contract to C++. C++ Standards Committee Paper N1613, 2004. http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2004/n1613.pdf (Eiffel and D have built-in language support for DBC.) DBC keywords This Library: No keyword -- it is a library. Code-based API (no keywords) follow Eiffel names: require(), ensure(), DBC_BODY(), .old (and .now), and DBC_INVARIANT(). Effiel: require, ensure, do, require else, ensure then, old, invariant, and result. D: in, out, body, invariant, and assert. C++ Std. Prop.: in, out, do, invariant, and return. On condition violation This Library: Throw (by default), terminate, or exit. Programmer can select action on violation using DBC_ASSERT() and DBC_ASSERT_STREAM(). Eiffel: Throw exception. D: Throw exception. C++ Std. Prop.: Terminate (by default), might throw or exit. Return value evaluation This Library: Yes. result argument of ensure() (only if postconditions compiled in object code). Eiffel: Yes, result keyword. D: No. C++ Std. Prop.: Yes, return keyword. Expression copying in postconditions ("old") This Library: Yes. For object and function arguments declared DBC_COPYABLE() or dbc::copyable, accessed via .old (only if postconditions compiled in object code and requires type to have copy constructor). Eiffel: Yes, old keyword. D: No. C++ Std. Prop.: Yes, in keyword. Subcontracting This Library: Yes. Use DBC_BASE() or B template parameter of dbc::fun::mem<> (but derived class programmer can decide to subcontract or not, recommended to always subcontract). Eiffel: Yes. D: Yes. C++ Std. Prop.: Yes. Assertion naming This Library: Yes. A string passed to DBC_ASSERT() and DBC_ASSERT_STREAM(). Eiffel: Yes. D: No. C++ Std. Prop.: No. Arbitrary code in contracts This Library: Yes. But recommended to keep contract code simple, ideally limit it to a list of assertions. Eiffel: No. D: Yes. C++ Std. Prop.: No. Contracts access level This Library: Any. Preconditions, postconditions, and invariants can access any class member public, protected, or private. But recommended to write contracts using public members as much as possible. In particular, preconditions should only use public members otherwise the caller will not be able to make sure the contract holds before invoking the function... Eiffel: Preconditions cannot access public members (to avoid contracts that cannot be checked by the caller). D: Any. C++ Std. Prop.: Any. Contract for abstract functions This Library: Yes. When body is defined pure virtual by "= 0;". Eiffel: Yes. D: No. C++ Std. Prop.: Yes. Code ordering This Library: Preconditions > postconditions > body (for macro-based API only). Eiffel: Order: Preconditions > body > postconditions. D: Order: Preconditions > postconditions > body. C++ Std. Prop.: Preconditions > postconditions > body. Static assertions This Library: Yes. Use C++ metaprogramming (e.g., the Boost.MPL library). Eiffel: No. D: Yes. C++ Std. Prop.: Yes. Prevent contract side-effects This Library: Yes. Use constant code block, constant object self, constant function arguments, and constant result to limit unintended contract side side-effects. Eiffel: Yes. D: No. C++ Std. Prop.: No. Contracts removable from object code This Library: Yes. Compilation and checking of preconditions, postconditions, invariants, and any of their combination can be enabled or disabled using the DBC_CHECK_... macros. Eiffel: Yes. D: Yes. C++ Std. Prop.: Only default assertions. Check invariants This Library: At end of constructors, at beginning and end of member functions, and at beginning of destructor (if programmer specifies contracts for those). E.g., programmer may omit contract for all private member functions so their calls will not check invariants. Furthermore, invariant checking in destructor is disabled during stack unwinding because of an unhandled exceptions (as contracts themselves can throw). Eiffel: At end of constructors, at beginning and end of public member functions. D: At end of constructors, at beginning and end of public member functions, and at beginning of destructor. C++ Std. Prop.: At end of constructors, at beginning and end of public member functions, and at beginning of destructor. Disabling assertion checking within assertions This Library: Yes. To prevent infinite recursion when checking contracts. Eiffel: Yes. D: No. C++ Std. Prop.: Yes. In nested function calls This Library: Disable invariants only. To prevent infinite recursion when checking contracts. Eiffel: Disable all assertions. D: Disable nothing. C++ Std. Prop.: Disable invariants only. Concurrency This Library: Not yet. To implement this similarly to Eiffel (i.e., making this library thread-safe and supporting waiting conditions...). Eiffel: Yes (implements waiting conditions). D: No. C++ Std. Prop.: No. Automatic contract documentation This Library: Yes. doxygen is used by default (see DBC_CONFIG_DOC_...). Eiffel: Yes (contracts are part of the class' "short form"). D: No with existing documentation tools. C++ Std. Prop.: No with existing documentation tools.