# 12.9.1 限制

由几种情况下，变量的改变并不会触发 watchpoint

因为 watchpoint 时绑定在符号上的，对于变量内部包含的对象的变化并不会触发监视机制。

此外，C code 可以直接修改一个变量，而不经过监视机制。

同样的原因导致的另外一个小限制是，只有动态绑定规则的变量可以被监视。这个解释起来也很简单，因为词法作用域的变量的变化可以很容易被任何代码觉察到。详情查阅 变量作用域章。


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