DesignByContract

"The benefits of Design by Contract include the following:
-A better understanding of the object-oriented method and, more generally, of software construction.
-A systematic approach to building bug-free object-oriented systems.
-An effective framework for debugging, testing and, more generally, quality assurance.
-A method for documenting software components.
-Better understanding and control of the inheritance mechanism.
-A technique for dealing with abnormal cases, leading to a safe and effective language construct for exception handling."
http://archive.eiffel.com/doc/manuals/technology/contract/page.html

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