为了达成这些目标，我们只需要在程序设计中制定一个规则：一个变量只赋值一次，而且永远不再修改它！

To accomplish these objectives, we need to make only one rule in our programming: Assign a value to a variable only once and NEVER MODIFY IT!

本地变量是仅可以在声明它的范围中和嵌套范围中使用的变量(也就是说，您可以向其赋值，也可以从中取值)。

A local variable is one that is only available for use (that is, you can assign to it, or fetch its value) within the scope in which it is declared, and within nested scopes as well.

这是本例子第一次把关联作为一个定义表达式(换句话说，一个赋值语句)的声明性陈述来使用，而不是用它作模型到模型的映射。

This is the first time that this example is using a relation as a declarative statement to define an expression (in other words, a value assignment) instead of using it for model-to-model mapping.

So that's the key thing to-- to realize; that what the assignment did was have two separate paths to the same object.

认识到赋值会造成两个独立的绑定到;,同一对象上这件事情很关键,因此我可以通过这一条或者。

OK, now that I've got that, we could think about what would I want to do with these points?

我也可以像以前那样，对它们进行赋值操作,好，现在我们已经有这些对象了？

Number three, pointer assignment, takes one pointer and changes it to point to the same pointee as another pointer so after the assignment the two pointers will point to the same pointee.

第三条，指针赋值，使一个指针,指向另外一个指针所指向的数据,赋值过后，两个指针会指向,同样的数据。