


Hasattr(), getattr(), setattr(), delattr() functions and sample codes in Python3
This article introduces the hasattr(), getattr(), setattr(), and delattr() functions in Python3 in detail through sample code. It is very good and has reference value. Friends who need it can refer to it
hasattr() function
hasattr() function is used to determine whether the corresponding attribute is included
Syntax:
hasattr(object,name)
Parameters:
object--object
name--string, attribute name
Return Value:
Returns True if the object has this attribute, otherwise returns False
Example:
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__) ##{'__module__': '__main__', 'country': 'China', '__init__': <function People.__init__ at 0x1006d5620>, 'people_info': <function People.people_info at 0x10205d1e0>, '__dict__': <attribute '__dict__' of 'People' objects>, '__weakref__': <attribute '__weakref__' of 'People' objects>, '__doc__': None}
getattr() function
Description:
getattr() function is used to return an object attribute value
Syntax :
getattr(object,name,default)
Parameters:
object--object
name--string , Object attribute
default--Default return value, if this parameter is not provided, AttributeError will be triggered when there is no attribute.
Return value:
Return object attribute value
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
## setattr() function
Description:setattr function, used to set attribute values, the attribute must existSyntax:setattr(object,name,value)
value--Attribute valueReturn value: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__) #{'__module__': '__main__', 'country': 'China', '__init__': <function People.__init__ at 0x1007d5620>, 'people_info': <function People.people_info at 0x10215d1e0>, '__dict__': <attribute '__dict__' of 'People' objects>, '__weakref__': <attribute '__weakref__' of 'People' objects>, '__doc__': None, 'x': 111}
delattr() function
Description: delattr function is used to delete attributesdelattr(x,'foobar) is equivalent to del x.foobar Syntax:setattr(object,name)
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__) {'__module__': '__main__', '__init__': <function People.__init__ at 0x1006d5620>, 'people_info': <function People.people_info at 0x10073d1e0>, '__dict__': <attribute '__dict__' of 'People' objects>, '__weakref__': <attribute '__weakref__' of 'People' objects>, '__doc__': 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()
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