Inheritance by extension is a common object-oriented design and is easily expressed through showing abstract classes in UML.

通过扩展来进行继承是一种常见的面向对象设计，很容易通过在U ML中显示抽象类来表达这种继承。

youdao

Because you have defined this extension to be invoked when the transformation is processing a UML class, you can safely type the target object to an Abstract Syntax Tree (AST) TypeDeclaration object.

因为当转换处理UM l类时，您已经定义调用该扩展，所以您可以安全地向Abstract Syntax Tree (ast) TypeDeclaration对象输入目标对象。

youdao

Observe that if the metaclass extension was to an abstract EClass, it will not show in the list.

注意到如果这个元类扩展以前是一个抽象的 EClass，它将不会显示在这个列表中。

youdao