一种CAD系统组件模型的组合技术及其实现

当前CAD系统中采用的组件模型主要有两类：标准组件模型和自定义组件模型。尽管这两种情况都有成功的例子，但是不能完全照搬成功经验。在分析了当前CAD开发中面临的挑战后，讨论了组件模型的选择策略，并给出了一个较好的解决方案——在标准组件模型的基础上增加一些新的特征和技术。最后，提出和实现了一个在COM组件模型基础上组件复用和扩展的新技术。

Composition techniques of CAD component model and its implementation

The component models used in CAD are mainly classified into two categories: standard component model and in-house component model.The successful experience should not be copied blindly,although there are some successful instances in both cases.After the analysis of the challenge in development of CAD,the selecting strategy of component model was discussed and an appropriate solution that enhanced some new features and techniques based on standard component model was given.At last,a new composition technique of component reused and extension based on COM was represented and implemented.This technique had two advantageous properties.It didn't change either the identity of the component being extended,or the Code of the component being extended.