blocks|key|1425870|text|#+Initialize+using+Parent
#
class+MySubClass(MySuperClass):
++++def+__init__(self):
++++++++MySuperClass.__init__(self)|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1425871|或者，更好的是，使用Python的内置函数super()+(请参阅Python+2/Python+3文档)可能是调用父函数进行初始化的一种稍好的方法：|unstyled|offset|length|style|CODE|1425872|#+Better+initialize+using+Parent+(less+redundant).
#
class+MySubClassBetter(MySuperClass):
++++def+__init__(self):
++++++++super(MySubClassBetter,+self).__init__()|1425873|或者，和上面一样，除了使用super()的零参数形式，它只在类定义中工作：|1425874|class+MySubClassBetter(MySuperClass):
++++def+__init__(self):
++++++++super().__init__()|1425875|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.python.org/2/library/functions.html#super|1|https://docs.python.org/3/library/functions.html#super^0|0|L|7|X|8|0|16|8|1|0|0|D|7|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|11|8|@$G|12|H|13|I|J]]|9|@$G|14|H|15|1|16]|$G|17|H|18|1|19]]|A|$]]|$1|K|3|L|5|6|7|1A|8|@]|9|@]|A|$B|C]]|$1|M|3|N|5|F|7|1B|8|@$G|1C|H|1D|I|J]]|9|@]|A|$]]|$1|O|3|P|5|6|7|1E|8|@]|9|@]|A|$B|C]]|$1|Q|3|-4|5|F|7|1F|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]|Y|$5|T|U|V|A|$W|Z]]]]

<pre><code># Initialize using Parent
#
class MySubClass(MySuperClass):
 def __init__(self):
 MySuperClass.__init__(self)
</code></pre>

Or, even better, the use of Python's built-in function, <code>super()</code> (see the <a href="http://docs.python.org/2/library/functions.html#super" rel="noreferrer">Python 2</a>/<a href="https://docs.python.org/3/library/functions.html#super" rel="noreferrer">Python 3</a> documentation for it) may be a slightly better method of calling the parent for initialization:

<pre><code># Better initialize using Parent (less redundant).
#
class MySubClassBetter(MySuperClass):
 def __init__(self):
 super(MySubClassBetter, self).__init__()
</code></pre>

Or, same exact thing as just above, except using the zero argument form of <code>super()</code>, which only works inside a class definition: 

<pre><code>class MySubClassBetter(MySuperClass):
 def __init__(self):
 super().__init__()
</code></pre>

blocks|key|1210905|text|一个英勇的小例子：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1210906|class+SuperHero(object):+#superclass,+inherits+from+default+object
++++def+getName(self):
++++++++raise+NotImplementedError+#you+want+to+override+this+on+the+child+classes

class+SuperMan(SuperHero):+#subclass,+inherits+from+SuperHero
++++def+getName(self):
++++++++return+"Clark+Kent"

class+SuperManII(SuperHero):+#another+subclass
++++def+getName(self):
+++++++return+"Clark+Kent,+Jr."

if+__name__+==+"__main__":
++++sm+=+SuperMan()
++++print+sm.getName()
++++sm2+=+SuperManII()
++++print+sm2.getName()|code-block|syntax|javascript|1210907|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

A heroic little example:

<pre><code>class SuperHero(object): #superclass, inherits from default object
 def getName(self):
 raise NotImplementedError #you want to override this on the child classes

class SuperMan(SuperHero): #subclass, inherits from SuperHero
 def getName(self):
 return "Clark Kent"

class SuperManII(SuperHero): #another subclass
 def getName(self):
 return "Clark Kent, Jr."

if __name__ == "__main__":
 sm = SuperMan()
 print sm.getName()
 sm2 = SuperManII()
 print sm2.getName()
</code></pre>

blocks|key|1210841|text|class+MySubClass(MySuperClass):
++++def+__init__(self):
++++++++MySuperClass.__init__(self)

++++++++#+<the+rest+of+your+custom+initialization+code+goes+here>|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1210842|python文档中的section+on+inheritance对此进行了更详细的说明|unstyled|offset|length|1210843|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.python.org/2/tutorial/classes.html^0|0|A|M|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|R|8|@]|9|@$G|S|H|T|1|U]]|A|$]]|$1|I|3|-4|5|F|7|V|8|@]|9|@]|A|$]]]|J|$K|$5|L|M|N|A|$O|P]]]]

<pre><code>class MySubClass(MySuperClass):
 def __init__(self):
 MySuperClass.__init__(self)

 # &lt;the rest of your custom initialization code goes here&gt;
</code></pre>

The <a href="http://docs.python.org/2/tutorial/classes.html" rel="noreferrer">section on inheritance</a> in the python documentation explains it in more detail

blocks|key|1210720|text|class+Class1(object):
++++pass

class+Class2(Class1):
++++pass|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1210721|Class2是Class1的子类|unstyled|1210722|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>class Class1(object):
 pass

class Class2(Class1):
 pass
</code></pre>

Class2 is a sub-class of Class1

blocks|key|1426021|text|在上面的答案中，super是在没有任何(关键字)参数的情况下初始化的。但是，您通常会希望这样做，并传递您自己的一些“自定义”参数。下面是一个示例，说明了这个用例：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1426022|class+SortedList(list):
++++def+__init__(self,+*args,+reverse=False,+**kwargs):
++++++++super().__init__(*args,+**kwargs)+++++++#+Initialize+the+super+class
++++++++self.reverse+=+reverse
++++++++self.sort(reverse=self.reverse)+++++++++#+Do+additional+things+with+the+custom+keyword+arguments|code-block|syntax|javascript|1426023|这是list的一个子类，它在初始化时会立即按照reverse关键字参数指定的方向对自身进行排序，如以下测试所示：|1426024|import+pytest

def+test_1():
++++assert+SortedList([5,+2,+3])+==+[2,+3,+5]

def+test_2():
++++SortedList([5,+2,+3],+reverse=True)+==+[5,+3,+2]

def+test_3():
++++with+pytest.raises(TypeError):
++++++++sorted_list+=+SortedList([5,+2,+3],+True)+++#+This+doesn't+work+because+'reverse'+must+be+passed+as+a+keyword+argument

if+__name__+==+"__main__":
++++pytest.main([__file__])|1426025|多亏了将*args传递给super，列表可以被初始化并填充条目，而不仅仅是空的。(请注意，根据PEP+3102，reverse是仅限关键字的参数)。|1426026|entityMap|0|LINK|mutability|MUTABLE|url|https://www.python.org/dev/peps/pep-3102/^0|8|5|0|0|2|4|N|7|0|0|4|5|C|5|1K|7|1B|8|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|11|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|12|8|@$9|13|A|14|B|C]|$9|15|A|16|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|17|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|18|8|@$9|19|A|1A|B|C]|$9|1B|A|1C|B|C]|$9|1D|A|1E|B|C]]|D|@$9|1F|A|1G|1|1H]]|E|$]]|$1|Q|3|-4|5|6|7|1I|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|X]]]]

In the answers above, the <code>super</code> is initialized without any (keyword) arguments. Often, however, you would like to do that, as well as pass on some 'custom' arguments of your own. Here is an example which illustrates this use case:

<pre><code>class SortedList(list):
 def __init__(self, *args, reverse=False, **kwargs):
 super().__init__(*args, **kwargs) # Initialize the super class
 self.reverse = reverse
 self.sort(reverse=self.reverse) # Do additional things with the custom keyword arguments
</code></pre>

This is a subclass of <code>list</code> which, when initialized, immediately sorts itself in the direction specified by the <code>reverse</code> keyword argument, as the following tests illustrate:

<pre><code>import pytest

def test_1():
 assert SortedList([5, 2, 3]) == [2, 3, 5]

def test_2():
 SortedList([5, 2, 3], reverse=True) == [5, 3, 2]

def test_3():
 with pytest.raises(TypeError):
 sorted_list = SortedList([5, 2, 3], True) # This doesn't work because 'reverse' must be passed as a keyword argument

if __name__ == "__main__":
 pytest.main([__file__])
</code></pre>

Thanks to the passing on of <code>*args</code> to <code>super</code>, the list can be initialized and populated with items instead of only being empty. (Note that <code>reverse</code> is a keyword-only argument in accordance with <a href="https://www.python.org/dev/peps/pep-3102/" rel="noreferrer">PEP 3102</a>).

blocks|key|1425938|text|还有另一种方法可以使用函数type()动态生成python中的子类|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1425939|SubClass+=+type('SubClass',+(BaseClass,),+{'set_x':+set_x})++#+Methods+can+be+set,+including+__init__()|code-block|syntax|javascript|1425940|在使用元类时，您通常希望使用此方法。当你想做一些底层的自动化时，这就改变了python创建类的方式。很可能你永远不需要这样做，但是当你这样做的时候，你就会知道你在做什么。|1425941|entityMap^0|D|6|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|S|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

There is another way to make subclasses in python dynamically with a function <code>type()</code>:

<pre><code>SubClass = type('SubClass', (BaseClass,), {'set_x': set_x}) # Methods can be set, including __init__()
</code></pre>

You usually want to use this method when working with metaclasses. When you want to do some lower level automations, that alters way how python creates class. Most likely you will not ever need to do it in this way, but when you do, than you already will know what you are doing.

blocks|key|1210688|text|class+Subclass+(SuperClass):
++++++#+Subclass+stuff+here|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1210689|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>class Subclass (SuperClass):
 # Subclass stuff here
</code></pre>

blocks|key|1425614|text|您可以使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1425615|class+DerivedClassName(BaseClassName):|code-block|syntax|javascript|1425616|有关详情，请参阅Python+docs,+section+9.5。|offset|length|1425617|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.python.org/2/tutorial/classes.html#inheritance^0|0|0|8|O|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

You use:

<pre><code>class DerivedClassName(BaseClassName):
</code></pre>

For details, see the <a href="https://docs.python.org/2/tutorial/classes.html#inheritance" rel="nofollow noreferrer">Python docs, section 9.5</a>.

blocks|key|1210857|text|class+Mammal(object):+
#mammal+stuff

class+Dog(Mammal):+
#doggie+stuff|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1210858|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>class Mammal(object): 
#mammal stuff

class Dog(Mammal): 
#doggie stuff
</code></pre>

blocks|key|1210882|text|Python中的子类化操作如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1210883|class+WindowElement:
++++def+print(self):
++++++++pass

class+Button(WindowElement):
++++def+print(self):
++++++++pass|code-block|syntax|javascript|1210884|这是一个关于Python的tutorial，也包含类和子类。|offset|length|1210885|entityMap|0|LINK|mutability|MUTABLE|url|http://www.gidnetwork.com/b-137.html^0|0|0|D|8|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

Subclassing in Python is done as follows:

<pre><code>class WindowElement:
 def print(self):
 pass

class Button(WindowElement):
 def print(self):
 pass
</code></pre>

Here is a <a href="http://www.gidnetwork.com/b-137.html" rel="nofollow noreferrer">tutorial</a> about Python that also contains classes and subclasses.

blocks|key|1211041|text|class+BankAccount:

++def+__init__(self,+balance=0):
++++self.balance+=+int(balance)

++def+checkBalance(self):+##+Checking+opening+balance....
++++return+self.balance

++def+deposit(self,+deposit_amount=1000):+##+takes+in+cash+deposit+amount+and+updates+the+balance+accordingly.
++++self.deposit_amount+=+deposit_amount
++++self.balance+%2B=+deposit_amount
++++return+self.balance

++def+withdraw(self,+withdraw_amount=500):+##+takes+in+cash+withdrawal+amount+and+updates+the+balance+accordingly
++++if+self.balance+<+withdraw_amount:+##+if+amount+is+greater+than+balance+return+`"invalid+transaction"`
++++++++return+'invalid+transaction'
++++else:
++++++self.balance+-=+withdraw_amount
++++++return+self.balance


class+MinimumBalanceAccount(BankAccount):+#subclass+MinimumBalanceAccount+of+the+BankAccount+class

++++def+__init__(self,balance=0,+minimum_balance=500):
++++++++BankAccount.__init__(self,+balance=0)
++++++++self.minimum_balance+=+minimum_balance
++++++++self.balance+=+balance+-+minimum_balance
++++++++#print+"Subclass+MinimumBalanceAccount+of+the+BankAccount+class+created!"

++++def+MinimumBalance(self):
++++++++return+self.minimum_balance

c+=+BankAccount()
print(c.deposit(50))
print(c.withdraw(10))

b+=+MinimumBalanceAccount(100,+50)
print(b.deposit(50))
print(b.withdraw(10))
print(b.MinimumBalance())|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1211042|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>class BankAccount:

 def __init__(self, balance=0):
 self.balance = int(balance)

 def checkBalance(self): ## Checking opening balance....
 return self.balance

 def deposit(self, deposit_amount=1000): ## takes in cash deposit amount and updates the balance accordingly.
 self.deposit_amount = deposit_amount
 self.balance += deposit_amount
 return self.balance

 def withdraw(self, withdraw_amount=500): ## takes in cash withdrawal amount and updates the balance accordingly
 if self.balance &lt; withdraw_amount: ## if amount is greater than balance return `"invalid transaction"`
 return 'invalid transaction'
 else:
 self.balance -= withdraw_amount
 return self.balance


class MinimumBalanceAccount(BankAccount): #subclass MinimumBalanceAccount of the BankAccount class

 def __init__(self,balance=0, minimum_balance=500):
 BankAccount.__init__(self, balance=0)
 self.minimum_balance = minimum_balance
 self.balance = balance - minimum_balance
 #print "Subclass MinimumBalanceAccount of the BankAccount class created!"

 def MinimumBalance(self):
 return self.minimum_balance

c = BankAccount()
print(c.deposit(50))
print(c.withdraw(10))

b = MinimumBalanceAccount(100, 50)
print(b.deposit(50))
print(b.withdraw(10))
print(b.MinimumBalance())
</code></pre>

blocks|key|1426068|text|这是一小段代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1426069|#+create+a+parent+class

class+Person(object):
++++def+__init__(self):
++++++++pass

++++def+getclass(self):
++++++++return+'I+am+a+Person'
#+create+two+subclass+from+Parent_class

class+Student(Person):
++++def+__init__(self):
++++++++super(Student,+self).__init__()

++++def+getclass(self):
++++++++return+'I+am+a+student'


class+Teacher(Person):
++++def+__init__(self):
++++++++super(Teacher,+self).__init__()

++++def+getclass(self):
++++++++return+'I+am+a+teacher'


person1+=+Person()
print(person1.getclass())

student1+=+Student()
print(student1.getclass())

teacher1+=+Teacher()
print(teacher1.getclass())|code-block|syntax|javascript|1426070|显示结果：|1426071|I+am+a+Person
I+am+a+student
I+am+a+teacher|1426072|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

this is a small code:
<pre class="lang-py prettyprint-override"><code># create a parent class

class Person(object):
 def __init__(self):
 pass

 def getclass(self):
 return 'I am a Person'
# create two subclass from Parent_class

class Student(Person):
 def __init__(self):
 super(Student, self).__init__()

 def getclass(self):
 return 'I am a student'


class Teacher(Person):
 def __init__(self):
 super(Teacher, self).__init__()

 def getclass(self):
 return 'I am a teacher'


person1 = Person()
print(person1.getclass())

student1 = Student()
print(student1.getclass())

teacher1 = Teacher()
print(teacher1.getclass())
</code></pre>
show result:
<pre class="lang-sh prettyprint-override"><code>I am a Person
I am a student
I am a teacher
</code></pre>

blocks|key|1426148|text|这是对@thompsongunner的answer的一个小补充。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1426149|要将参数传递给您的超类(父类)，只需使用父类的函数签名：|1426150|class+MySubClassBetter(MySuperClass):
++++def+__init__(self,+someArg,+someKwarg="someKwarg"):
++++++++super().__init__(someArg,+someKwarg=someKwarg)|code-block|syntax|javascript|1426151|调用父类的__init__()方法就像构造其他类一样，这就是为什么不需要包含self的原因。|style|CODE|1426152|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/users/69718/thompsongunner|1|https://stackoverflow.com/a/1608905/2103784^0|3|F|0|J|6|1|0|0|0|5|A|12|4|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@$A|Z|B|10|1|11]|$A|12|B|13|1|14]]|C|$]]|$1|D|3|E|5|6|7|15|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|16|8|@]|9|@]|C|$I|J]]|$1|K|3|L|5|6|7|17|8|@$A|18|B|19|M|N]|$A|1A|B|1B|M|N]]|9|@]|C|$]]|$1|O|3|-4|5|6|7|1C|8|@]|9|@]|C|$]]]|P|$Q|$5|R|S|T|C|$U|V]]|W|$5|R|S|T|C|$U|X]]]]

A minor addition to <a href="https://stackoverflow.com/users/69718/thompsongunner">@thompsongunner</a>'s <a href="https://stackoverflow.com/a/1608905/2103784">answer</a>.
To pass args to your superclass (parent), just use the function signature of the parent class:
<pre><code>class MySubClassBetter(MySuperClass):
 def __init__(self, someArg, someKwarg=&quot;someKwarg&quot;):
 super().__init__(someArg, someKwarg=someKwarg)
</code></pre>
You are calling the parent's <code>__init__()</code> method as if you are constructing any other class which is why you don't need to include <code>self</code>.

问Python:如何从超类创建一个子类？
EN

回答 13

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问Python:如何从超类创建一个子类？EN

回答 13

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问Python:如何从超类创建一个子类？
EN