Python a day---difficult to understand the phenomenon + clear explanation---We are all the same

? Deep down, we're all the same *

class WTF:  pass

Output:

>>> WTF() == WTF() # 两个不同的对象不相等False>>> WTF() is WTF() # id一样不相等False>>> hash(WTF()) == hash(WTF()) # 哈希值也“应该”不相等True>>> id(WTF()) == id(WTF())True

Explain:

• When id a function is used, Python creates an WTF object named and passes it to the id function. The id function gets its id (its memory location) and discards the object.
• When we do this in the interaction, Python will give the object a new location if it finds an object that occupies an unused memory location.

• But why use is the comparison results False ? Let's take a look.

  class WTF(object):def __init__(self): print("I") # 创建时触发def __del__(self): print("D") #丢弃时触发

  Output:

  >>> WTF() is WTF()I  # 创建1I  # 创建2，比较，内存位置不同，返回falseD # 删除1D # 删除2False>>> id(WTF()) == id(WTF())I #创建1D #记住内存，连同内存一起删掉I #创建2，它用了1的内存（因为1已经删掉），比较，两个内存相同。D #删除2True

Python a day---difficult to understand the phenomenon + clear explanation---We are all the same