Python的高级特性11:拓展基本数据类型(dict)

字典的创建有两种方式,如果出现In [26]这样的赋值方式就会报错。

In [17]: s['name'] = 'alex'

In [18]: s['sex'] = 'male'

In [19]: s
Out[19]: {'name': 'alex', 'sex': 'male'}

In [20]: s = {'name':'alex','sex':'male'}

In [21]: s
Out[21]: {'name': 'alex', 'sex': 'male'}

In [22]: t = {}

In [23]: t['name'] = 'lilei'

In [24]: t['sex'] = 'male'

In [25]: t
Out[25]: {'name': 'lilei', 'sex': 'male'}

In [26]: t.name = 'hanmeimei'
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-26-62e0b27ded5b> in <module>()
----> 1 t.name = 'hanmeimei'

AttributeError: 'dict' object has no attribute 'name'

但我这个人很固执,就对这种方式情有独钟，迫切希望Python可以拓展这个属性,该怎么办呢？最好的办法就是自己来拓展。

t.name = 'hanmeimei' 这样的set方式明显是__setter__行为,那么我只需要重写__setter__方法就可以了。

class StrongerDict(dict):
    def __getattr__(self, key):
        return self[key]

    def __setattr__(self, key, value):
        self[key] = value

    def __call__(self, key):
        return self[key]

s = StrongerDict()
#__setattr__方法
s.name = 'alex'
#dict本身赋值方法不受影响，因为重写的是__setattr__方法
s['sex'] = 'male'
print(s)
#__getattr__方法
print(s.name)

运行结果是:

/System/Library/Frameworks/Python.framework/Versions/3.4/bin/python3 /Users/lsf/PycharmProjects/py3Project/test3.py
{'sex': 'male', 'name': 'alex'}
alex

Process finished with exit code 0