[已解决]类变量和实例变量的区别

kking1 · 发表于 2023-3-5 09:08:11

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import copy                                                 # 引入 copy 模块
class aa:
s2 = None
def __init__(self):
      self.s1 = None
      self.s2 = None

def asa(self,bb):
      self.s1 = bb
      aa.s2 = self.s1                         # 用深拷贝
      return aa.s2

      #return self.s2
def sadsa(self):
      self.s1.id = 3
class bb:
def __init__(self):
      self.id = 0

def setId(self,id):
      self.id = id

c = bb()
c.setId(2)
#print(c.id)
d = aa()
d.asa(c)
d.sadsa()
print(d.s2.id)
#print(d.asa(c).id)
#print(c.id)

把s2从实例变量改成类变量后为什么会报错呢？

最佳答案

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isdkz

2023-3-5 09:34:18

因为实例变量把类变量给覆盖掉了

import copy class aa: s2 = None def __init__(self): self.s1 = None self.s2 = None def asa(self,bb): self.s1 = bb aa.s2 = self.s1 return aa.s2 #return self.s2 def sadsa(self): self.s1.id = 3 class bb: def __init__(self): self.id = 0 def setId(self,id): self.id = id c = bb() c.setId(2) #print(c.id) d = aa() d.asa(c) d.sadsa() print(aa.s2.id) # 这里把 d 改成 aa 不会报错 #print(d.asa(c).id) #print(c.id)
import copy class aa: s2 = None def __init__(self): self.s1 = None self.s2 = None # 这里初始化了实例变量，就是这个把类变量给覆盖了 def asa(self,bb): self.s1 = bb aa.s2 = self.s1 del self.s2 # 删掉实例变量 return aa.s2 #return self.s2 def sadsa(self): self.s1.id = 3 class bb: def __init__(self): self.id = 0 def setId(self,id): self.id = id c = bb() c.setId(2) #print(c.id) d = aa() d.asa(c) d.sadsa() print(d.s2.id) #print(d.asa(c).id) #print(c.id)

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isdkz · 发表于 2023-3-5 09:34:18

因为实例变量把类变量给覆盖掉了

import copy class aa: s2 = None def __init__(self): self.s1 = None self.s2 = None def asa(self,bb): self.s1 = bb aa.s2 = self.s1 return aa.s2 #return self.s2 def sadsa(self): self.s1.id = 3 class bb: def __init__(self): self.id = 0 def setId(self,id): self.id = id c = bb() c.setId(2) #print(c.id) d = aa() d.asa(c) d.sadsa() print(aa.s2.id) # 这里把 d 改成 aa 不会报错 #print(d.asa(c).id) #print(c.id)
import copy class aa: s2 = None def __init__(self): self.s1 = None self.s2 = None # 这里初始化了实例变量，就是这个把类变量给覆盖了 def asa(self,bb): self.s1 = bb aa.s2 = self.s1 del self.s2 # 删掉实例变量 return aa.s2 #return self.s2 def sadsa(self): self.s1.id = 3 class bb: def __init__(self): self.id = 0 def setId(self,id): self.id = id c = bb() c.setId(2) #print(c.id) d = aa() d.asa(c) d.sadsa() print(d.s2.id) #print(d.asa(c).id) #print(c.id)

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