A library that offers in a light-weight manner Design by Contract constructs

Currently C++ 11/14 does not support natively the concept of Design by Contract. Several libraries are available that support Design by Contract, but all that I know of, use heavily preprocessor makros. So this is my attempt to support this feature with pure C++.

This library supports pre-condition, post-condition and invariants for classes and structs. Simple example of a rectangular implementation.

class Rect 
{
  // Use this define if an invariant is defined. If no invariant is defined
  // no need to do it
  CONTRACTOR
  int w_;
  int h_;
public:
  Rect() : w_(0), h_(0) {}
  
  ~Rect() {
    // checking that the invariants are fulfilled, even before destruction
    INVARIANT;
  }
  
  void setWidth(int newW) {
    // setting the pre condition of this method; the invariant is checked 
    // once at the end of the scope
    PRECONDITION [&] { return newW >= 0; };
    // setting the post condition; the invariant is checked only once after 
    // leaving the scope, regardless of the number of pre- and/or post-conditions
    POSTCONDITION [&, this] { return newW == w_; };
    w_ = newW;
    
    // There is no need to define here INVARIANT here. This is done automatically
    // whenever there is a bool invariant() const method is defined
  }
  
  int size() const {
    int result;
    POSTCONDITION [&] { return result == w_ * h_; }
    result = w_ * h_;
    
    return result;
  }
  
  bool invariant() const {
    return w_ >= 0 && h_ >= 0;
  }
};

Felix Petriconi (felix at petriconi.net)

Comments, feedback or contributions are welcome!

Boost 1.0 License

0.1

• C++ 11 (partly, as far as Visual Studio 2013 supports it)
• CMake 2.8 or later
• GoogleTest 1.7 (Is part of the repository, because it's CMakeFiles.txt needs some patches to compile with Visual Studio)

• Clone into e.g. D:\misc\contract_light
• Create a build folder, eg D:\misc\contract_light_build
• Open a command prompt in that contract_light_build
• Have CMake in the path
• Execute cmake -G "Visual Studio 11 Win64" ..\contract_light_build
• Open created solution in .\alb_build\AllocatorBuilder.sln
• Compile and run all test

• Clone into e.g. ~/contract_light via "git clone http://github.com/FelixPetriconi/contract_light"
• Call mkdir contract_light_build && cd contract_light_build
• Call cmake -G "Unix Makefiles" ../contract_light
• Build and test with make && ./test/contract_light_test

to be done