如何在字典中重复键时提高错误 [英] How to raise error if duplicates keys in dictionary
问题描述
如果用户在字典中输入重复键,我会尝试引发错误。该字典在一个文件中,用户可以手动编辑文件。
I try to raise an error if the user enter a duplicate key in a dictionary. The dictionary is in a file and the user can edit the file manually.
示例:
dico= {'root':{
'a':{'some_key':'value',...},
'b':{'some_key':'value',...},
'c':{'some_key':'value',...},
...
'a':{'some_key':'value',...},
}
}
新密钥'a'已经存在...
the new key 'a' already exist...
当我从文件加载dico时,如何测试dico并警告用户?
How can I test dico and warn the user when I load dico from the file?
推荐答案
编写dict的子类,覆盖__setitem__,以便在替换现有密钥时引发错误;重写文件以使用您的新子类的构造函数而不是默认的dict内置。
Write a subclass of dict, override __setitem__ such that it throws an error when replacing an existing key; rewrite the file to use your new subclass's constructor instead of the default dict built-ins.
import collections
class Dict(dict):
def __init__(self, inp=None):
if isinstance(inp,dict):
super(Dict,self).__init__(inp)
else:
super(Dict,self).__init__()
if isinstance(inp, (collections.Mapping, collections.Iterable)):
si = self.__setitem__
for k,v in inp:
si(k,v)
def __setitem__(self, k, v):
try:
self.__getitem__(k)
raise ValueError("duplicate key '{0}' found".format(k))
except KeyError:
super(Dict,self).__setitem__(k,v)
那么你的文件将被写为
dico = Dict(
('root', Dict(
('a', Dict(
('some_key', 'value'),
('another_key', 'another_value')
),
('b', Dict(
('some_key', 'value')
),
('c', Dict(
('some_key', 'value'),
('another_key', 'another_value')
),
....
)
)
使用元组代替文件导入的dict(使用{}符号编写,它将使用默认的dict构造函数,并且重复的将在Dict构造函数获取它们之前消失!)。
using tuples instead of dicts for the file import (written using the {} notation, it would use the default dict constructor, and the duplicates would disappear before the Dict constructor ever gets them!).
这篇关于如何在字典中重复键时提高错误的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!