为了在一种有效的方式下做到这一点，我们需要一种机制来描述个体所属的类以及这些个体通过类成员关系而继承得到的属性。
In order to do this in a useful fashion we need to have a mechanism to describe the classes that individuals belong to and the properties that they inherit by virtue of class membership.
不同的实现使用不同的对象类来指定用户和组信息，并且使用不同的方法定义组成员关系。
Different implementations use different object classes to specify user and group information, and different ways of defining group membership.
当类的变量被声明为类的成员变量时，找到所有权关系是更加可靠的。
It was more reliable at finding ownership relationships when the variables were declared as member variables of the class.
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