为什么我被允许以这种方式改变“自我”：
self.map! {|x| x*2}
或者这样：
self.replace(self.map {|x| x*2})
但不是这样的：
self = self.map {|x| x*2}
为什么Ruby不允许我更改“self”变量指向的对象,但允许我更改对象的属性？
解决方法
不是答案,只是一个线索.
a=[1,2]
=>[1,2]
a.object_id
=>2938
a.map!{|x| x*2}
=>[2,4]
a.object_id # different data but still the same object
=>2938
a.replace(a.map {|x| x*2})
=>[4,8]
a.object_id # different data but still the same object
=>2938
a = a.map{|x| x*2} # .map will create a new object assign to a
=>[8,16]
a.object_id #different object
=>2940
你无法将自己改变为另一个.
