If you assign one class instance variable to another, not only do they have the same data type, they point to the same class instance in memory.

如果将一个类实例变量赋给另一个类，它们不仅具有相同的数据类型，还在内存中指向相同的类实例。

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An assertion cannot be used with class variable declarations for instance, but can be placed within any method.

不能将断言同实例的类变量声明一块使用，但却可以将其置于任何方法内。

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In the change that follows, it stores a reference to the view part instance in a class variable.

在随后进行更改时，将视图部件实例的引用存储到一个类变量中。

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