47 lines
1.2 KiB
Python
47 lines
1.2 KiB
Python
'''
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desc：尝试定义一种新的数据类型
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等差数列
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'''
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class ArithemeticSequence:
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def __init__(self, start=0, step=1):
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print('Call function __init__')
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self.start = start
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self.step = step
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self.myData = {}
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# 定义获取值的方法
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def __getitem__(self, key):
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print('Call function __getitem__')
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try:
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return self.myData[key]
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except KeyError:
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return self.start + key * self.step
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# 定义赋值方法
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def __setitem__(self, key, value):
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print('Call function __setitem__')
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self.myData[key] = value
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# 定义获取长度的方法
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def __len__(self):
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print('Call function __len__')
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return len(self.myData)
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# 定义删除元素的方法
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def __delitem__(self, key):
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print('Call function __delitem__')
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del self.myData[key]
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s = ArithemeticSequence(1, 2)
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print(s[0])
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print(s[1])
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print(s[2])
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print(s[3])# 这里应该执行self.start+key*self.step，因为没有3这个key
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s[3] = 100 # 进行赋值
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print(s[3]) # 前面进行了赋值，那么直接输出赋的值100
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print(len(s))
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del s[3] # 删除3这个key |