Hasattr(), getattr(), setattr(), delattr() functions and sample codes in Python3

class People:

  country='China'

  def __init__(self,name):

    self.name=name

  def people_info(self):

    print('%s is xxx' %(self.name))

obj=People('aaa')

print(hasattr(People,'country'))

#返回值：True

print('country' in People.__dict__)

#返回值：True

print(hasattr(obj,'people_info'))

#返回值：True

print(People.__dict__)

##{&#39;__module__&#39;: &#39;__main__&#39;, &#39;country&#39;: &#39;China&#39;, &#39;__init__&#39;: <function People.__init__ at 0x1006d5620>, &#39;people_info&#39;: <function People.people_info at 0x10205d1e0>, &#39;__dict__&#39;: <attribute &#39;__dict__&#39; of &#39;People&#39; objects>, &#39;__weakref__&#39;: <attribute &#39;__weakref__&#39; of &#39;People&#39; objects>, &#39;__doc__&#39;: None}

class People:

  country='China'

  def __init__(self,name):

    self.name=name

  def people_info(self):

    print('%s is xxx' %(self.name))

obj=getattr(People,'country')

print(obj)

#返回值China

#obj=getattr(People,'countryaaaaaa')

#print(obj)

#报错

# File "/getattr()函数.py", line 32, in <module>

#   obj=getattr(People,'countryaaaaaa')

# AttributeError: type object 'People' has no attribute 'countryaaaaaa'

obj=getattr(People,'countryaaaaaa',None)

print(obj)

#返回值None

class People:

  country='China'

  def __init__(self,name):

    self.name=name

  def people_info(self):

    print('%s is xxx' %(self.name))

obj=People('aaa')

setattr(People,'x',111) #等同于People.x=111

print(People.x)

#obj.age=18

setattr(obj,'age',18)

print(obj.__dict__)

#{'name': 'aaa', 'age': 18}

print(People.__dict__)

#{&#39;__module__&#39;: &#39;__main__&#39;, &#39;country&#39;: &#39;China&#39;, &#39;__init__&#39;: <function People.__init__ at 0x1007d5620>, &#39;people_info&#39;: <function People.people_info at 0x10215d1e0>, &#39;__dict__&#39;: <attribute &#39;__dict__&#39; of &#39;People&#39; objects>, &#39;__weakref__&#39;: <attribute &#39;__weakref__&#39; of &#39;People&#39; objects>, &#39;__doc__&#39;: None, &#39;x&#39;: 111}

class People:

  country='China'

  def __init__(self,name):

    self.name=name

  def people_info(self):

    print('%s is xxx' %(self.name))

delattr(People,'country') #等同于del People.country

print(People.__dict__)

{&#39;__module__&#39;: &#39;__main__&#39;, &#39;__init__&#39;: <function People.__init__ at 0x1006d5620>, &#39;people_info&#39;: <function People.people_info at 0x10073d1e0>, &#39;__dict__&#39;: <attribute &#39;__dict__&#39; of &#39;People&#39; objects>, &#39;__weakref__&#39;: <attribute &#39;__weakref__&#39; of &#39;People&#39; objects>, &#39;__doc__&#39;: None}

class Foo:

  def run(self):

    while True:

      cmd=input('cmd>>: ').strip()

      if hasattr(self,cmd):

        func=getattr(self,cmd)

        func()

  def download(self):

    print('download....')

  def upload(self):

    print('upload...')

# obj=Foo()

# obj.run()