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地方变量(例如变量、全球变量和类别变量)之间的差别如何?
原标题:What is the difference between local variables, instance variables, global variables, and class variables?

I m just learning Ruby and have and have an extremely beginner question. Is the difference between the four types of variables mainly just scope. So local variables can only be used within the current block, instance variables within the current instance, global variables within every scope and finally, class variables within the current class? Thanks a lot!

最佳回答

You ve got it right although there are some wrinkles. Class variables (@@foo) can be accessed both from the class methods and the instance methods of a class.

在继承方面,他们有点不.:如果你在基数类别中确定这种变数,并再次将其归入子类,那么你将改变等级中所有阶层的价值。 如果你重新使用类别变量来储存环境,这往往不是你想要的——你想要子类能够从基类中“过度”价值,而实际上不将其改变为基类。 铁路提供<条码>等值:它制造了具有这种行为的通道方法。

最后,实际上并不是一种单独的类型,但是由于类别是物体,因此也有类别变数。 这与继承无关,每个阶层的主体都有完全独立的等级。 与类别变数不同的是,这种情况可能直接干扰类别变数。

问题回答

你这样做是正确的。 差异只是范围。

你们能够直觉地看到这一点。 差异只是范围(无论记忆中处理的方式有多大差别)。





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