【脚本语言系列】关于Python基础知识对象变动，你知道的事

如何控制对象可变性

• 对象可变性(mutation)，可变（mutable）

# -*- coding:utf-8 -*-the_name = ['Allen']print the_nameother_name = the_nameother_name += ['Moore']print other_nameprint the_name

['Allen']['Allen', 'Moore']['Allen', 'Moore']

# -*- coding:utf-8 -*-def append_to(item, target=[]):    target.append(item)    return targettarget=append_to(12)print targettarget=append_to(23)print targettarget=append_to(34)print target

[12][12, 23][12, 23, 34]

• 不可变(immutable)

# -*- coding:utf-8 -*-def append_to(item, target=None):    if target is None:        target = []    target.append(item)    return targettarget=append_to(12)print targettarget=append_to(23)print targettarget=append_to(34)print target

[12][23][34]