什么？浮游物是一成不变的吗？但是我不能
x = 5.0x += 7.0print x # 12.0
那不是
“ mut” x吗？
好吧，你同意字符串是不可变的，对吗？但是你可以做同样的事情。
s = 'foo's += 'bar'print s # foobar
变量的值会更改，但是会通过更改变量引用的内容来更改。一个可变的类型可以改变这种方式，它可也 “到位”而改变。
这是区别。
x = something # immutable typeprint xfunc(x)print x # prints the same thingx = something # mutable typeprint xfunc(x)print x # might print something differentx = something # immutable typey = xprint x# some statement that operates on yprint x # prints the same thingx = something # mutable typey = xprint x# some statement that operates on yprint x # might print something different
具体例子
x = 'foo'y = xprint x # fooy += 'bar'print x # foox = [1, 2, 3]y = xprint x # [1, 2, 3]y += [3, 2, 1]print x # [1, 2, 3, 3, 2, 1]def func(val): val += 'bar'x = 'foo'print x # foofunc(x)print x # foodef func(val): val += [3, 2, 1]x = [1, 2, 3]print x # [1, 2, 3]func(x)print x # [1, 2, 3, 3, 2, 1]
