Python3 中hasattr()、getattr()、setattr()、delattr()函數及範例程式碼-Python教學-PHP中文網

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Python3 中hasattr()、getattr()、setattr()、delattr()函數及範例程式碼

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Apr 18, 2018 am 11:10 AM

delattrgetattr

本文透過範例程式碼給大家詳細介紹了Python3 中hasattr()、getattr()、setattr()、delattr()函數，非常不錯，具有參考借鑒價值，需要的朋友參考下吧

hasattr()函數

hasattr()函數用來判斷是否包含對應的屬性

語法：

hasattr(object,name)

參數：

object--物件

name--字串，屬性名稱

傳回值：

如果物件有該屬性傳回True，否則傳回False

範例：

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}

##getattr()函數

描述：

getattr()函數用來傳回一個物件屬性值

語法：

getattr(object,name,default)

#參數：

object--物件

##name--字串，物件屬性

default--預設回傳值，如果不提供該參數，在沒有對於屬性時，將觸發AttributeError。

傳回值：

傳回物件屬性值

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

setattr()函數描述：

setattr函數，用於設定屬性值，該屬性必須存在

語法：

setattr(object,name,value)

參數：

object--物件

##name--字串，物件屬性

value--屬性值

傳回值：

無

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}

delattr()函數

描述：

delattr函數用來刪除屬性

delattr(x,'foobar)相當於del x.foobar

語法：

setattr(object,name)

參數：

object--物件

name--必須是物件的屬性

傳回值：

無

#範例：

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}

補充範例：

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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