Python3 中hasattr()、getattr()、setattr()、delattr()函数及示例代码-Python教程-PHP中文网

Python3 中hasattr()、getattr()、setattr()、delattr()函数及示例代码

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发布： 2018-04-18 11:10:41

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本文通过示例代码给大家详细介绍了Python3 中hasattr()、getattr()、setattr()、delattr()函数，非常不错，具有参考借鉴价值，需要的朋友参考下吧

hasattr()函数

hasattr()函数用于判断是否包含对应的属性

语法：

hasattr(object,name)

参数：

object--对象

name--字符串，属性名

返回值：

如果对象有该属性返回True，否则返回False

示例：

class People:
  country=&#39;China&#39;
  def __init__(self,name):
    self.name=name
  def people_info(self):
    print(&#39;%s is xxx&#39; %(self.name))
obj=People(&#39;aaa&#39;)
print(hasattr(People,&#39;country&#39;))
#返回值：True
print(&#39;country&#39; in People.__dict__)
#返回值：True
print(hasattr(obj,&#39;people_info&#39;))
#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}

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getattr()函数

描述：

getattr()函数用于返回一个对象属性值

语法：

getattr(object,name,default)

参数：

object--对象

name--字符串，对象属性

default--默认返回值，如果不提供该参数，在没有对于属性时，将触发AttributeError。

返回值：

返回对象属性值

class People:
  country=&#39;China&#39;
  def __init__(self,name):
    self.name=name

  def people_info(self):
    print(&#39;%s is xxx&#39; %(self.name))
obj=getattr(People,&#39;country&#39;)
print(obj)
#返回值China
#obj=getattr(People,&#39;countryaaaaaa&#39;)
#print(obj)
#报错
# File "/getattr()函数.py", line 32, in <module>
#   obj=getattr(People,&#39;countryaaaaaa&#39;)
# AttributeError: type object &#39;People&#39; has no attribute &#39;countryaaaaaa&#39;
obj=getattr(People,&#39;countryaaaaaa&#39;,None)
print(obj)
#返回值None

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setattr()函数

描述：

setattr函数，用于设置属性值，该属性必须存在

语法：

setattr(object,name,value)

参数：

object--对象

name--字符串，对象属性

value--属性值

返回值：

无

class People:
  country=&#39;China&#39;
  def __init__(self,name):
    self.name=name
  def people_info(self):
    print(&#39;%s is xxx&#39; %(self.name))
obj=People(&#39;aaa&#39;)
setattr(People,&#39;x&#39;,111) #等同于People.x=111
print(People.x)
#obj.age=18
setattr(obj,&#39;age&#39;,18)
print(obj.__dict__)
#{&#39;name&#39;: &#39;aaa&#39;, &#39;age&#39;: 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}

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delattr()函数

描述：

delattr函数用于删除属性

delattr(x,'foobar)相当于del x.foobar

语法：

setattr(object,name)

参数：

object--对象

name--必须是对象的属性

返回值：

无

示例：

class People:
  country=&#39;China&#39;
  def __init__(self,name):
    self.name=name
  def people_info(self):
    print(&#39;%s is xxx&#39; %(self.name))
delattr(People,&#39;country&#39;) #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}

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补充示例：

class Foo:
  def run(self):
    while True:
      cmd=input(&#39;cmd>>: &#39;).strip()
      if hasattr(self,cmd):
        func=getattr(self,cmd)
        func()
  def download(self):
    print(&#39;download....&#39;)
  def upload(self):
    print(&#39;upload...&#39;)
# obj=Foo()
# obj.run()

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