Understanding of instance attributes and class attributes

# class fun():
# a = 1 # class attribute
#     def l(self):
#         a = 4
#         print('a')
# b = fun()
# print(fun.a)



# class Test(object):
#     name = 'scolia'
#
# a = Test()
# Test.name = 'scolia good' # Modify class attributes through classes, success! Even the instance properties have been changed
# print(Test.name)
# print(a.name)


# class Test(object):
#     name = 'scolia'
#
# a = Test()
# a.name = 'scolia good' # Modifying through an instance is unsuccessful, but it is equivalent to re-creating the instance attribute without modifying the class attribute
# print(Test.name)
# print(a.name)

# The situation here is that I access a property in the instance, but I don't have it in the instance, so I try to create my class to find out if there is this property.
# If found, there is, if not found, throw an exception. (This shows that instance objects can access class properties! Conversely, class objects cannot access instance properties!)
# And when I try to use the instance to modify a property that is immutable in the class, I don't actually modify it, but create the property in my instance.
# And when I access this property again, I have it in the instance, so I don't have to look for it in the class.

# class Test(object):
#     name = 'scolia'
#
# a = Test()
# a.abc = 123
# print(dir(Test)) # abc is automatically created in instance properties
# print (dir)


# Having confirmed that instance properties can be modified by class objects, try modifying class properties by instance
# class Test:
#     list1 = []
#
# a = Test()
# a.list1.append(123) # Modify the list in the class by instance
# print(Test.list1)
# print(a.list1)


# You can also arbitrarily add methods to an instance, python supports adding attributes dynamically
# class Test:
#     pass
#
# def fangfa():
# print('I am a method of an instance')
#
# a = Test()
# b = Test()
# a.abc = fangfa # Deliberately add a method
# a.abc()
# b.abc() # b does not have this method

# You can also dynamically add methods to classes
class Test:
    pass

def fangfa(self): # self represents an instance method, which can only be called by an instance
    print('I am a method')

Test.abc = fangfa
a = Test()
a.abc()
b = Test() # The method of the class has been modified (added)
b.abc()