blocks|key|359654|text|是的，所有的Python类都应该扩展(或者说子类，这里是Python+)对象。虽然通常不会发生严重的问题，但在某些情况下(如多继承树)，这将是重要的。这也确保了与Python+3更好的兼容性。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|359655|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Yes, all Python classes should extend (or rather subclass, this is Python here) object. While normally no serious problems will occur, in some cases (as with multiple inheritance trees) this will be important. This also ensures better compatibility with Python 3.

blocks|key|359685|text|在Python3中，类隐式地扩展object，无论您自己是否这样说。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|359686|在Python2中，有old-style+and+new-style类。要表示一个类是新样式的，您必须显式地从object继承。如果不是，则使用旧式实现。|359687|您通常需要一个新样式的类。显式继承自object。请注意，这也适用于旨在与Python+2兼容的Python+3代码。|359688|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.python.org/release/2.5.2/ref/node33.html^0|G|6|0|1J|6|B|N|0|0|I|6|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@$9|X|A|Y|1|Z]]|E|$]]|$1|H|3|I|5|6|7|10|8|@$9|11|A|12|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|Q]]]]

In Python 3, classes extend <code>object</code> implicitly, whether you say so yourself or not.

In Python 2, there's <a href="http://docs.python.org/release/2.5.2/ref/node33.html" rel="noreferrer">old-style and new-style</a> classes. To signal a class is new-style, you have to inherit explicitly from <code>object</code>. If not, the old-style implementation is used.

You generally want a new-style class. Inherit from <code>object</code> explicitly. Note that this also applies to Python 3 code that aims to be compatible with Python 2.

blocks|key|359737|text|在python3中没有什么不同，但是在python2中，不扩展object会给您带来旧式类；您可能希望使用新式类而不是旧式类。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|359738|entityMap^0|V|6|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

in python3 there isn't a differance, but in python2 not extending <code>object</code> gives you an old-style classes; you'd like to use a new-style class over an old-style class.

blocks|key|359801|text|在Python2中，不继承object将创建一个旧式类，这会导致type产生不同的结果：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|359802|>>>+class+Foo:+pass
...+
>>>+type(Foo())
<type+'instance'>|code-block|syntax|javascript|359803|与|359804|>>>+class+Bar(object):+pass
...+
>>>+type(Bar())
<class+'__main__.Bar'>|359805|此外，多重继承的规则是different，我甚至不想在这里进行总结。我所见过的关于MI的所有优秀文档都描述了新样式的类。|359806|最后，旧式类在Python3中消失了，从object继承变得隐式。所以，除非你需要向后兼容旧的软件，否则总是喜欢新风格的类。|359807|entityMap|0|LINK|mutability|MUTABLE|url|http://www.python.org/download/releases/2.2.3/descrintro/^0|D|6|W|4|0|0|0|0|B|9|0|0|K|6|0^^$0|@$1|2|3|4|5|6|7|10|8|@$9|11|A|12|B|C]|$9|13|A|14|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|15|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|16|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|17|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|18|8|@]|D|@$9|19|A|1A|1|1B]]|E|$]]|$1|Q|3|R|5|6|7|1C|8|@$9|1D|A|1E|B|C]]|D|@]|E|$]]|$1|S|3|-4|5|6|7|1F|8|@]|D|@]|E|$]]]|T|$U|$5|V|W|X|E|$Y|Z]]]]

In Python 2, not inheriting from <code>object</code> will create an old-style class, which, amongst other effects, causes <code>type</code> to give different results:

<pre><code>&gt;&gt;&gt; class Foo: pass
... 
&gt;&gt;&gt; type(Foo())
&lt;type 'instance'&gt;
</code></pre>

vs.

<pre><code>&gt;&gt;&gt; class Bar(object): pass
... 
&gt;&gt;&gt; type(Bar())
&lt;class '__main__.Bar'&gt;
</code></pre>

Also the rules for multiple inheritance are <a href="http://www.python.org/download/releases/2.2.3/descrintro/">different</a> in ways that I won't even try to summarize here. All good documentation that I've seen about MI describes new-style classes.

Finally, old-style classes have disappeared in Python 3, and inheritance from <code>object</code> has become implicit. So, always prefer new style classes unless you need backward compat with old software.

I have found that both of the following work:

<pre><code>class Foo():
 def a(self):
 print "hello"

class Foo(object):
 def a(self):
 print "hello"
</code></pre>

Should all Python classes extend object? Are there any potential problems with not extending object?

Should all Python classes extend object?

Python

我发现以下两项工作都完成了：class Foo():    def a(self):        print "hello"class Foo(object):    def a(self):        print "hello"所有的Python类都应该扩展object吗？不扩展对象会有什么潜在的问题吗？

问所有的Python类都应该扩展object吗？
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