最近的Ruby for Rails读书笔记

1，module的mix-in
两个module定义同一方法，都include后，后include的module的方法有效

2，全局变量以$开头
Ruby自带的全局变量有
$:表示在你load外部文件时Ruby搜索的path
$$表示Ruby进程ID

3，self的指代
[code]
Context Example Which object is self?
Top level of program Any code outside of other blocks main(built-in top-level default object)
Class definition class C The class object C
Module definition module M The module object M
Method definitions 1. Top level main(built-in top-level default object)
def method_name
2. Instance method definition An instance of C, responding to method_name
class C
def method_name
3. Instance method definition in module I. Individual object extended by M
module M II. Instance of class that mixes in M
def method_name
4. Singleton method(including class obj
methods)
def obj.method_name
[/code]

4，定义与Ruby内建类重名的类的时候，如定义Violin::String，我们要在Violin里调用Ruby内建的String类时，使用::String

5，Ruby三种作用域，public/protected/private，默认为public
private方法不能使用explicit receiver，只能被implicit receiver self调用，如可以method_name，而不能obj.method_name
protected方法的调用保证了self的class和被调用的另一个对象的class相同

6，top-level方法为Kernel模块的private instance methods