python - 从字典中的自定义函数访问值

Question

我有以下针对特定用例的代码行。 (使用python 2.7)

class AutoMap(dict):
    """Implementation of autovivification feature."""
    def __getitem__(self, item):
        try:
            return dict.__getitem__(self, item)
        except KeyError:
            value = self[item] = type(self)()
            return value
    def __dir__(self):
        return dict.keys()
    __getattr__ = dict.get
    __setattr__ = dict.__setitem__
    __delattr__ = dict.__delitem__

obj = AutoMap()
AddressMap = AutoMap()

obj["state"] = "Maharastra"
obj["country"] = "India"

AddressMap['address1'] = obj

obj["state"] = "California"
obj["country"] = "USA"

AddressMap['address2'] = obj

print AddressMap # {'address1': {'state' : 'Maharastra', 'country' : 'India'}, 'address2': {'state' : 'California', 'country' : 'USA'}}

def prn_state():
    print "State: " + state


AddressMap['address1']['_prn_state'] = prn_state

AddressMap['address2']['_prn_state'] = prn_state


print AddressMap # {'address1': {'state' : 'Maharastra', 'country' : 'India', '_prn_state': <function prn_state at 0x7fb297dc7320>}, 'address2': {'state' : 'California', 'country' : 'USA', '_prn_state': <function prn_state at 0x7fb297dc7320>}}

print type(AddressMap) # <class 'AutoMap'>

print AddressMap.address2._prn_state()

现在，我希望每当我编写这行代码时它都应该打印“California”。但是，它会抛出一条错误消息“NameError:全局名称‘state’未定义”

Answer 1

AddressMap是一个dict，获取address2的state值:

AddressMap = {'address1': {'state' : 'Maharastra', 'country' : 'India'}, 
              'address2': {'state' : 'California', 'country' : 'USA'}}    
print(AddressMap['address2']['state'])

编辑:

包装在函数中:

def states(AddressMap, address):
    return AddressMap[address].get('state', 'Not found')

AddressMap = {'address1': {'state' : 'Maharastra', 'country' : 'India'}, 'address2': {'state' : 'California', 'country' : 'USA'}}
print(states(AddressMap, 'address2'))

输出:

California