针对基于原型的单继承面向对象模型，通过扩展库的形式实现了Lua对契约式开发的支持，包括原型不变式、

函数前后置断言。利用了语言提供的动态元机制在运行期改变某些语法构造的原始语义。最后分析了该实现方法的弱点

和改进思路。-Single inheritance for prototype-based object-oriented model, achieved by extending the database in the form of a Lua development of contractual support, including the prototype of the same type, function before and after the home assertion. Use of the language mechanisms of dynamic element of change in the operation of certain grammatical structures of the original semantics. Finally, analysis of the weaknesses of the realization and improvement ideas.