php：为什么我们需要设置类成员的可见性？ [关闭]
问题描述：
I know, by using protected or private, we can limit the visibility of a member in a class. But I'm curious about the purpose of doing so. Calling a class name($a = new class B) doesn't make its members global. So, why still need to protect its members?
我知道，通过使用protected或private，我们可以限制类中成员的可见性。 但我很好奇这样做的目的。 调用类名（ $ a = new class B code>）不会使其成员成为全局。 那么，为什么还需要保护其成员？ p>
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答
For low coupling and high cohesion
Please check below:
http://www.hokstad.com/why-coupling-is-always-bad-cohesion-vs-coupling