{"id":10021225,"date":"2026-02-01T02:39:32","date_gmt":"2026-01-31T18:39:32","guid":{"rendered":"https:\/\/itmax.cn\/?p=10021225"},"modified":"2026-02-01T02:39:32","modified_gmt":"2026-01-31T18:39:32","slug":"python%e4%b8%ad%e7%9a%84%e5%85%83%e7%b1%bb%e7%bc%96%e7%a8%8b%e4%b8%8e%e7%b1%bb%e6%9e%84%e9%80%a0%e6%9c%ba%e5%88%b6%e6%b7%b1%e5%ba%a6%e8%a7%a3%e6%9e%90","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10021225","title":{"rendered":"Python\u4e2d\u7684\u5143\u7c7b\u7f16\u7a0b\u4e0e\u7c7b\u6784\u9020\u673a\u5236\u6df1\u5ea6\u89e3\u6790"},"content":{"rendered":"<h2>Python\u4e2d\u7684\u5143\u7c7b\u7f16\u7a0b\u4e0e\u7c7b\u6784\u9020\u673a\u5236\u6df1\u5ea6\u89e3\u6790<\/h2>\n<h3>1. \u5143\u7c7b\u7684\u57fa\u672c\u6982\u5ff5<\/h3>\n<h4>1.1 \u4ec0\u4e48\u662f\u5143\u7c7b<\/h4>\n<p>\u5143\u7c7b\uff08Metaclass\uff09\u662fPython\u4e2d\u521b\u5efa\u7c7b\u7684\u7c7b\uff0c\u662f\u7c7b\u7684\u6a21\u677f\u3002\u5728Python\u4e2d\uff0c\u4e00\u5207\u7686\u5bf9\u8c61\uff0c\u7c7b\u672c\u8eab\u4e5f\u662f\u5bf9\u8c61\uff0c\u800c\u5143\u7c7b\u5c31\u662f\u521b\u5efa\u8fd9\u4e9b\u7c7b\u5bf9\u8c61\u7684\u5de5\u5382\u3002<\/p>\n<h4>1.2 \u7c7b\u4e0e\u5143\u7c7b\u7684\u5173\u7cfb<\/h4>\n<ul>\n<li><strong>\u5bf9\u8c61<\/strong>\uff1a\u7531\u7c7b\u521b\u5efa\u7684\u5b9e\u4f8b<\/li>\n<li><strong>\u7c7b<\/strong>\uff1a\u7531\u5143\u7c7b\u521b\u5efa\u7684\u5b9e\u4f8b<\/li>\n<li><strong>\u5143\u7c7b<\/strong>\uff1a\u521b\u5efa\u7c7b\u7684\u7c7b\uff0c\u9ed8\u8ba4\u662f<code>type<\/code><\/li>\n<\/ul>\n<pre><code class=\"python\"># \u67e5\u770b\u7c7b\u7684\u5143\u7c7b\nclass MyClass:\n    pass\n\nprint(type(MyClass))  # &lt;class 'type'&gt;\nprint(type(type))     # &lt;class 'type'&gt;<\/code><\/pre>\n<h4>1.3 \u5143\u7c7b\u7684\u4f5c\u7528<\/h4>\n<ul>\n<li>\u63a7\u5236\u7c7b\u7684\u521b\u5efa\u8fc7\u7a0b<\/li>\n<li>\u4fee\u6539\u7c7b\u7684\u5c5e\u6027\u548c\u65b9\u6cd5<\/li>\n<li>\u5b9e\u73b0\u5355\u4f8b\u6a21\u5f0f\u3001\u6ce8\u518c\u8868\u6a21\u5f0f\u7b49\u8bbe\u8ba1\u6a21\u5f0f<\/li>\n<li>\u81ea\u52a8\u6ce8\u518c\u7c7b\u3001\u6dfb\u52a0\u65b9\u6cd5\u6216\u5c5e\u6027<\/li>\n<li>\u5b9e\u73b0ORM\u6846\u67b6\u7b49\u9ad8\u7ea7\u529f\u80fd<\/li>\n<\/ul>\n<h3>2. type\u5143\u7c7b<\/h3>\n<h4>2.1 type\u7684\u57fa\u672c\u7528\u6cd5<\/h4>\n<p><code>type<\/code>\u662fPython\u7684\u5185\u7f6e\u5143\u7c7b\uff0c\u5b83\u6709\u4e24\u79cd\u7528\u6cd5\uff1a<\/p>\n<ol>\n<li><strong>\u67e5\u770b\u5bf9\u8c61\u7c7b\u578b<\/strong>\uff1a<code>type(object)<\/code><\/li>\n<li><strong>\u52a8\u6001\u521b\u5efa\u7c7b<\/strong>\uff1a<code>type(name, bases, namespace)<\/code><\/li>\n<\/ol>\n<pre><code class=\"python\"># \u52a8\u6001\u521b\u5efa\u7c7b\nMyDynamicClass = type('MyDynamicClass', (), {\n    'greeting': 'Hello',\n    'say_hello': lambda self: print(self.greeting)\n})\n\ninstance = MyDynamicClass()\ninstance.say_hello()  # \u8f93\u51fa: Hello<\/code><\/pre>\n<h4>2.2 type\u521b\u5efa\u7c7b\u7684\u8fc7\u7a0b<\/h4>\n<ol>\n<li><strong>\u540d\u79f0<\/strong>\uff1a\u7c7b\u7684\u540d\u79f0<\/li>\n<li><strong>\u57fa\u7c7b<\/strong>\uff1a\u7c7b\u7ee7\u627f\u7684\u7236\u7c7b\u5143\u7ec4<\/li>\n<li><strong>\u547d\u540d\u7a7a\u95f4<\/strong>\uff1a\u7c7b\u7684\u5c5e\u6027\u548c\u65b9\u6cd5\u5b57\u5178<\/li>\n<\/ol>\n<pre><code class=\"python\"># \u5e26\u6709\u7ee7\u627f\u7684\u52a8\u6001\u7c7b\u521b\u5efa\nclass BaseClass:\n    def base_method(self):\n        print(&quot;Base method&quot;)\n\nDerivedClass = type('DerivedClass', (BaseClass,), {\n    'derived_method': lambda self: print(&quot;Derived method&quot;)\n})\n\ninstance = DerivedClass()\ninstance.base_method()    # \u8f93\u51fa: Base method\ninstance.derived_method()  # \u8f93\u51fa: Derived method<\/code><\/pre>\n<h3>3. \u81ea\u5b9a\u4e49\u5143\u7c7b<\/h3>\n<h4>3.1 \u7ee7\u627ftype\u521b\u5efa\u5143\u7c7b<\/h4>\n<pre><code class=\"python\">class MyMetaclass(type):\n    def __new__(mcs, name, bases, namespace):\n        # \u5728\u7c7b\u521b\u5efa\u4e4b\u524d\u4fee\u6539\n        namespace['added_by_metaclass'] = 'This attribute was added by the metaclass'\n        return super().__new__(mcs, name, bases, namespace)\n    \n    def __init__(cls, name, bases, namespace):\n        # \u5728\u7c7b\u521b\u5efa\u4e4b\u540e\u521d\u59cb\u5316\n        print(f&quot;Initializing class {name}&quot;)\n        super().__init__(name, bases, namespace)\n\n# \u4f7f\u7528\u81ea\u5b9a\u4e49\u5143\u7c7b\nclass MyClass(metaclass=MyMetaclass):\n    def __init__(self, value):\n        self.value = value\n\nprint(MyClass.added_by_metaclass)  # \u8f93\u51fa: This attribute was added by the metaclass<\/code><\/pre>\n<h4>3.2 <strong>new<\/strong> vs <strong>init<\/strong><\/h4>\n<ul>\n<li><strong><strong>new<\/strong><\/strong>\uff1a\u521b\u5efa\u7c7b\u5bf9\u8c61\uff0c\u8fd4\u56de\u65b0\u521b\u5efa\u7684\u7c7b<\/li>\n<li><strong><strong>init<\/strong><\/strong>\uff1a\u521d\u59cb\u5316\u5df2\u521b\u5efa\u7684\u7c7b\u5bf9\u8c61\uff0c\u65e0\u8fd4\u56de\u503c<\/li>\n<\/ul>\n<h4>3.3 \u5143\u7c7b\u7684\u65b9\u6cd5\u89e3\u6790\u987a\u5e8f<\/h4>\n<p>\u5f53\u8c03\u7528\u7c7b\u7684\u65b9\u6cd5\u65f6\uff0cPython\u4f1a\u6309\u7167\u4ee5\u4e0b\u987a\u5e8f\u67e5\u627e\uff1a<\/p>\n<ol>\n<li>\u5b9e\u4f8b\u7684<code>__dict__<\/code><\/li>\n<li>\u7c7b\u7684<code>__dict__<\/code><\/li>\n<li>\u7236\u7c7b\u7684<code>__dict__<\/code><\/li>\n<li>\u5143\u7c7b\u7684<code>__dict__<\/code><\/li>\n<li>\u7236\u5143\u7c7b\u7684<code>__dict__<\/code><\/li>\n<\/ol>\n<h3>4. \u5143\u7c7b\u7684\u9ad8\u7ea7\u5e94\u7528<\/h3>\n<h4>4.1 \u5b9e\u73b0\u5355\u4f8b\u6a21\u5f0f<\/h4>\n<pre><code class=\"python\">class SingletonMeta(type):\n    _instances = {}\n    \n    def __call__(cls, *args, **kwargs):\n        if cls not in cls._instances:\n            cls._instances[cls] = super().__call__(*args, **kwargs)\n        return cls._instances[cls]\n\nclass SingletonClass(metaclass=SingletonMeta):\n    def __init__(self, value):\n        self.value = value\n\n# \u6d4b\u8bd5\u5355\u4f8b\ninstance1 = SingletonClass(42)\ninstance2 = SingletonClass(100)\nprint(instance1 is instance2)  # \u8f93\u51fa: True\nprint(instance1.value)         # \u8f93\u51fa: 42\nprint(instance2.value)         # \u8f93\u51fa: 42<\/code><\/pre>\n<h4>4.2 \u81ea\u52a8\u6ce8\u518c\u7c7b<\/h4>\n<pre><code class=\"python\">class RegistryMeta(type):\n    _registry = {}\n    \n    def __init__(cls, name, bases, namespace):\n        super().__init__(name, bases, namespace)\n        if name != 'BasePlugin':  # \u8df3\u8fc7\u57fa\u7c7b\n            cls._registry[name] = cls\n\nclass BasePlugin(metaclass=RegistryMeta):\n    pass\n\nclass PluginA(BasePlugin):\n    pass\n\nclass PluginB(BasePlugin):\n    pass\n\nprint(BasePlugin._registry)  # \u8f93\u51fa: {'PluginA': &lt;class 'PluginA'&gt;, 'PluginB': &lt;class 'PluginB'&gt;}<\/code><\/pre>\n<h4>4.3 \u81ea\u52a8\u6dfb\u52a0\u65b9\u6cd5<\/h4>\n<pre><code class=\"python\">class MethodAdderMeta(type):\n    def __new__(mcs, name, bases, namespace):\n        # \u4e3a\u6240\u6709\u7c7b\u6dfb\u52a0debug\u65b9\u6cd5\n        namespace['debug'] = lambda self: print(f&quot;Debugging {name} instance&quot;)\n        return super().__new__(mcs, name, bases, namespace)\n\nclass MyClass(metaclass=MethodAdderMeta):\n    pass\n\ninstance = MyClass()\ninstance.debug()  # \u8f93\u51fa: Debugging MyClass instance<\/code><\/pre>\n<h4>4.4 \u5b9e\u73b0\u5c5e\u6027\u9a8c\u8bc1<\/h4>\n<pre><code class=\"python\">class ValidatedMeta(type):\n    def __new__(mcs, name, bases, namespace):\n        # \u5904\u7406\u5e26\u9a8c\u8bc1\u5668\u7684\u5c5e\u6027\n        for key, value in namespace.items():\n            if hasattr(value, 'validate'):\n                # \u521b\u5efa\u5c5e\u6027\u63cf\u8ff0\u7b26\n                def getter(self, k=key):\n                    return getattr(self, f'_{k}')\n                \n                def setter(self, val, k=key, v=value):\n                    if v.validate(val):\n                        setattr(self, f'_{k}', val)\n                    else:\n                        raise ValueError(f&quot;Invalid value for {k}&quot;)\n                \n                namespace[key] = property(getter, setter)\n        \n        return super().__new__(mcs, name, bases, namespace)\n\n# \u9a8c\u8bc1\u5668\u793a\u4f8b\nclass IntegerValidator:\n    def __init__(self, min_val=None, max_val=None):\n        self.min_val = min_val\n        self.max_val = max_val\n    \n    def validate(self, value):\n        if not isinstance(value, int):\n            return False\n        if self.min_val is not None and value &lt; self.min_val:\n            return False\n        if self.max_val is not None and value &gt; self.max_val:\n            return False\n        return True\n\nclass Person(metaclass=ValidatedMeta):\n    age = IntegerValidator(min_val=0, max_val=120)\n    \n    def __init__(self, age):\n        self.age = age\n\n# \u6d4b\u8bd5\nperson = Person(25)\nprint(person.age)  # \u8f93\u51fa: 25\n\n# person.age = &quot;twenty&quot;  # \u4f1a\u5f15\u53d1ValueError\n# person.age = 150       # \u4f1a\u5f15\u53d1ValueError<\/code><\/pre>\n<h3>5. \u7c7b\u6784\u9020\u673a\u5236<\/h3>\n<h4>5.1 \u7c7b\u7684\u521b\u5efa\u8fc7\u7a0b<\/h4>\n<ol>\n<li><strong>\u5143\u7c7b\u7684__new__<\/strong>\uff1a\u521b\u5efa\u7c7b\u5bf9\u8c61<\/li>\n<li><strong>\u5143\u7c7b\u7684__init__<\/strong>\uff1a\u521d\u59cb\u5316\u7c7b\u5bf9\u8c61<\/li>\n<li><strong>\u7c7b\u7684__init_subclass__<\/strong>\uff1a\u5b50\u7c7b\u521d\u59cb\u5316\u65f6\u8c03\u7528<\/li>\n<li><strong>\u7c7b\u7684__class_getitem__<\/strong>\uff1a\u652f\u6301\u7c7b\u7684\u4e0b\u6807\u64cd\u4f5c\uff08\u5982<code>List[int]<\/code>\uff09<\/li>\n<\/ol>\n<h4>5.2 __init_subclass__\u65b9\u6cd5<\/h4>\n<p>Python 3.6+ \u5f15\u5165\u7684\u7279\u6027\uff0c\u7528\u4e8e\u5728\u5b50\u7c7b\u521b\u5efa\u65f6\u6267\u884c\u4ee3\u7801\uff1a<\/p>\n<pre><code class=\"python\">class Base:\n    def __init_subclass__(cls, **kwargs):\n        super().__init_subclass__(**kwargs)\n        print(f&quot;Initializing subclass: {cls.__name__}&quot;)\n        cls.registered = True\n\nclass Derived(Base):\n    pass\n\nprint(Derived.registered)  # \u8f93\u51fa: True<\/code><\/pre>\n<h4>5.3 __class_getitem__\u65b9\u6cd5<\/h4>\n<p>Python 3.7+ \u5f15\u5165\u7684\u7279\u6027\uff0c\u7528\u4e8e\u652f\u6301\u7c7b\u7684\u4e0b\u6807\u64cd\u4f5c\uff1a<\/p>\n<pre><code class=\"python\">class GenericArray:\n    def __class_getitem__(cls, item):\n        return f&quot;Array of {item}&quot;\n\nprint(GenericArray[int])    # \u8f93\u51fa: Array of &lt;class 'int'&gt;\nprint(GenericArray[str])    # \u8f93\u51fa: Array of &lt;class 'str'&gt;<\/code><\/pre>\n<h4>5.4 __prepare__\u65b9\u6cd5<\/h4>\n<p>\u5143\u7c7b\u7684<code>__prepare__<\/code>\u65b9\u6cd5\u7528\u4e8e\u5728\u521b\u5efa\u7c7b\u7684\u547d\u540d\u7a7a\u95f4\u4e4b\u524d\u51c6\u5907\u547d\u540d\u7a7a\u95f4\uff1a<\/p>\n<pre><code class=\"python\">class OrderedMeta(type):\n    @classmethod\n    def __prepare__(mcs, name, bases):\n        return dict()  # \u53ef\u4ee5\u8fd4\u56de\u81ea\u5b9a\u4e49\u7684\u6620\u5c04\u5bf9\u8c61\n\nclass OrderedClass(metaclass=OrderedMeta):\n    a = 1\n    b = 2\n    c = 3<\/code><\/pre>\n<h3>6. \u5143\u7c7b\u7684\u6700\u4f73\u5b9e\u8df5<\/h3>\n<h4>6.1 \u4f55\u65f6\u4f7f\u7528\u5143\u7c7b<\/h4>\n<ul>\n<li><strong>\u590d\u6742\u573a\u666f<\/strong>\uff1a\u9700\u8981\u6df1\u5ea6\u63a7\u5236\u7c7b\u7684\u521b\u5efa\u8fc7\u7a0b<\/li>\n<li><strong>\u6846\u67b6\u5f00\u53d1<\/strong>\uff1a\u5982ORM\u3001\u5e8f\u5217\u5316\u5e93\u7b49<\/li>\n<li><strong>\u4ee3\u7801\u751f\u6210<\/strong>\uff1a\u81ea\u52a8\u751f\u6210\u91cd\u590d\u4ee3\u7801<\/li>\n<li><strong>\u6a21\u5f0f\u5b9e\u73b0<\/strong>\uff1a\u5355\u4f8b\u3001\u6ce8\u518c\u8868\u7b49\u6a21\u5f0f<\/li>\n<\/ul>\n<h4>6.2 \u66ff\u4ee3\u65b9\u6848<\/h4>\n<p>\u5728\u5f88\u591a\u60c5\u51b5\u4e0b\uff0c\u53ef\u4ee5\u4f7f\u7528\u66f4\u7b80\u5355\u7684\u66ff\u4ee3\u65b9\u6848\uff1a<\/p>\n<ul>\n<li><strong>\u88c5\u9970\u5668<\/strong>\uff1a\u4fee\u6539\u7c7b\u6216\u51fd\u6570<\/li>\n<li><strong>\u7c7b\u88c5\u9970\u5668<\/strong>\uff1a\u4fee\u6539\u7c7b\u7684\u5c5e\u6027\u548c\u65b9\u6cd5<\/li>\n<li><strong>\u7ee7\u627f<\/strong>\uff1a\u901a\u8fc7\u57fa\u7c7b\u63d0\u4f9b\u901a\u7528\u529f\u80fd<\/li>\n<li><strong>Mixin<\/strong>\uff1a\u901a\u8fc7\u6df7\u5165\u7c7b\u6dfb\u52a0\u529f\u80fd<\/li>\n<\/ul>\n<h4>6.3 \u5143\u7c7b\u7684\u4f18\u7f3a\u70b9<\/h4>\n<p><strong>\u4f18\u70b9<\/strong>\uff1a<\/p>\n<ul>\n<li>\u5f3a\u5927\u7684\u63a7\u5236\u80fd\u529b<\/li>\n<li>\u53ef\u4ee5\u5b9e\u73b0\u590d\u6742\u7684\u8bbe\u8ba1\u6a21\u5f0f<\/li>\n<li>\u51cf\u5c11\u91cd\u590d\u4ee3\u7801<\/li>\n<\/ul>\n<p><strong>\u7f3a\u70b9<\/strong>\uff1a<\/p>\n<ul>\n<li>\u589e\u52a0\u4ee3\u7801\u590d\u6742\u5ea6<\/li>\n<li>\u96be\u4ee5\u7406\u89e3\u548c\u8c03\u8bd5<\/li>\n<li>\u53ef\u80fd\u4e0e\u5176\u4ed6\u5143\u7c7b\u51b2\u7a81<\/li>\n<li>\u8fc7\u5ea6\u4f7f\u7528\u4f1a\u4f7f\u4ee3\u7801\u96be\u4ee5\u7ef4\u62a4<\/li>\n<\/ul>\n<h3>7. \u5143\u7c7b\u7684\u5b9e\u9645\u5e94\u7528\u6848\u4f8b<\/h3>\n<h4>7.1 ORM\u6846\u67b6\u5b9e\u73b0<\/h4>\n<pre><code class=\"python\">class ModelMeta(type):\n    def __new__(mcs, name, bases, namespace):\n        if name == 'Model':\n            return super().__new__(mcs, name, bases, namespace)\n        \n        # \u63d0\u53d6\u5b57\u6bb5\u5b9a\u4e49\n        fields = {}\n        for key, value in namespace.items():\n            if isinstance(value, Field):\n                fields[key] = value\n        \n        # \u4fdd\u5b58\u5b57\u6bb5\u4fe1\u606f\n        namespace['_fields'] = fields\n        return super().__new__(mcs, name, bases, namespace)\n\nclass Field:\n    def __init__(self, type_):\n        self.type = type_\n\nclass Model(metaclass=ModelMeta):\n    pass\n\nclass User(Model):\n    id = Field('integer')\n    name = Field('string')\n    email = Field('string')\n\nprint(User._fields)  # \u8f93\u51fa\u5b57\u6bb5\u5b9a\u4e49<\/code><\/pre>\n<h4>7.2 \u63d2\u4ef6\u7cfb\u7edf<\/h4>\n<pre><code class=\"python\">class PluginRegistry(type):\n    _plugins = {}\n    \n    def __init__(cls, name, bases, namespace):\n        super().__init__(name, bases, namespace)\n        if name != 'Plugin':\n            plugin_name = namespace.get('plugin_name', name)\n            cls._plugins[plugin_name] = cls\n\nclass Plugin(metaclass=PluginRegistry):\n    plugin_name = None\n    \n    def execute(self):\n        raise NotImplementedError\n\nclass HelloPlugin(Plugin):\n    plugin_name = 'hello'\n    \n    def execute(self):\n        return &quot;Hello, World!&quot;\n\nclass GoodbyePlugin(Plugin):\n    plugin_name = 'goodbye'\n    \n    def execute(self):\n        return &quot;Goodbye, World!&quot;\n\n# \u4f7f\u7528\u63d2\u4ef6\nprint(Plugin._plugins['hello']().execute())  # \u8f93\u51fa: Hello, World!\nprint(Plugin._plugins['goodbye']().execute())  # \u8f93\u51fa: Goodbye, World!<\/code><\/pre>\n<h4>7.3 \u5355\u4f8b\u6a21\u5f0f\u7684\u9ad8\u7ea7\u5b9e\u73b0<\/h4>\n<pre><code class=\"python\">class ThreadSafeSingletonMeta(type):\n    _instances = {}\n    _lock = threading.Lock()\n    \n    def __call__(cls, *args, **kwargs):\n        if cls not in cls._instances:\n            with cls._lock:\n                if cls not in cls._instances:\n                    cls._instances[cls] = super().__call__(*args, **kwargs)\n        return cls._instances[cls]\n\nclass ThreadSafeSingleton(metaclass=ThreadSafeSingletonMeta):\n    pass<\/code><\/pre>\n<h3>8. \u5143\u7c7b\u4e0ePython\u7279\u6027\u7684\u4ea4\u4e92<\/h3>\n<h4>8.1 \u5143\u7c7b\u4e0e\u88c5\u9970\u5668<\/h4>\n<pre><code class=\"python\">class MetaWithDecorator(type):\n    def __new__(mcs, name, bases, namespace):\n        # \u4e3a\u6240\u6709\u65b9\u6cd5\u6dfb\u52a0\u88c5\u9970\u5668\n        for key, value in namespace.items():\n            if callable(value) and not key.startswith('__'):\n                def decorator(func):\n                    def wrapper(*args, **kwargs):\n                        print(f&quot;Calling {key}&quot;)\n                        return func(*args, **kwargs)\n                    return wrapper\n                namespace[key] = decorator(value)\n        return super().__new__(mcs, name, bases, namespace)\n\nclass MyClass(metaclass=MetaWithDecorator):\n    def do_something(self):\n        print(&quot;Doing something&quot;)\n\ninstance = MyClass()\ninstance.do_something()  # \u8f93\u51fa: Calling do_something\n                         # \u8f93\u51fa: Doing something<\/code><\/pre>\n<h4>8.2 \u5143\u7c7b\u4e0e\u63cf\u8ff0\u7b26<\/h4>\n<pre><code class=\"python\">class Descriptor:\n    def __get__(self, instance, owner):\n        return f&quot;Value from {owner.__name__}&quot;\n\nclass MetaWithDescriptor(type):\n    def __new__(mcs, name, bases, namespace):\n        namespace['descriptor'] = Descriptor()\n        return super().__new__(mcs, name, bases, namespace)\n\nclass MyClass(metaclass=MetaWithDescriptor):\n    pass\n\nprint(MyClass.descriptor)  # \u8f93\u51fa: Value from MyClass<\/code><\/pre>\n<h4>8.3 \u5143\u7c7b\u4e0e\u7ee7\u627f<\/h4>\n<pre><code class=\"python\">class BaseMeta(type):\n    def __init__(cls, name, bases, namespace):\n        super().__init__(name, bases, namespace)\n        print(f&quot;BaseMeta initializing {name}&quot;)\n\nclass DerivedMeta(BaseMeta):\n    def __init__(cls, name, bases, namespace):\n        super().__init__(name, bases, namespace)\n        print(f&quot;DerivedMeta initializing {name}&quot;)\n\nclass BaseClass(metaclass=BaseMeta):\n    pass\n\nclass DerivedClass(BaseClass, metaclass=DerivedMeta):\n    pass<\/code><\/pre>\n<h3>9. \u5143\u7c7b\u7684\u8c03\u8bd5\u6280\u5de7<\/h3>\n<h4>9.1 \u67e5\u770b\u7c7b\u7684\u521b\u5efa\u8fc7\u7a0b<\/h4>\n<pre><code class=\"python\">class DebugMeta(type):\n    def __new__(mcs, name, bases, namespace):\n        print(f&quot;Creating class {name}&quot;)\n        print(f&quot;Bases: {bases}&quot;)\n        print(f&quot;Namespace keys: {list(namespace.keys())}&quot;)\n        return super().__new__(mcs, name, bases, namespace)\n\nclass DebugClass(metaclass=DebugMeta):\n    pass<\/code><\/pre>\n<h4>9.2 \u8ffd\u8e2a\u5143\u7c7b\u65b9\u6cd5\u8c03\u7528<\/h4>\n<pre><code class=\"python\">class TraceMeta(type):\n    def __new__(mcs, name, bases, namespace):\n        print(f&quot;TraceMeta.__new__ called for {name}&quot;)\n        return super().__new__(mcs, name, bases, namespace)\n    \n    def __init__(cls, name, bases, namespace):\n        print(f&quot;TraceMeta.__init__ called for {name}&quot;)\n        super().__init__(name, bases, namespace)\n    \n    def __call__(cls, *args, **kwargs):\n        print(f&quot;TraceMeta.__call__ called for {cls.__name__}&quot;)\n        return super().__call__(*args, **kwargs)\n\nclass TraceClass(metaclass=TraceMeta):\n    def __init__(self):\n        print(f&quot;TraceClass.__init__ called&quot;)\n\ninstance = TraceClass()<\/code><\/pre>\n<h3>10. \u603b\u7ed3<\/h3>\n<p>\u5143\u7c7b\u662fPython\u4e2d\u6700\u5f3a\u5927\u3001\u6700\u5e95\u5c42\u7684\u7279\u6027\u4e4b\u4e00\uff0c\u5b83\u5141\u8bb8\u5f00\u53d1\u8005\u6df1\u5ea6\u63a7\u5236\u7c7b\u7684\u521b\u5efa\u548c\u884c\u4e3a\u3002\u901a\u8fc7\u5143\u7c7b\uff0c\u53ef\u4ee5\u5b9e\u73b0\u8bb8\u591a\u9ad8\u7ea7\u529f\u80fd\uff0c\u5982ORM\u6846\u67b6\u3001\u63d2\u4ef6\u7cfb\u7edf\u3001\u5355\u4f8b\u6a21\u5f0f\u7b49\u3002<\/p>\n<h4>\u5173\u952e\u8981\u70b9<\/h4>\n<ol>\n<li><strong>\u5143\u7c7b\u662f\u521b\u5efa\u7c7b\u7684\u7c7b<\/strong>\uff0c\u9ed8\u8ba4\u662f<code>type<\/code><\/li>\n<li><strong>type\u53ef\u4ee5\u52a8\u6001\u521b\u5efa\u7c7b<\/strong>\uff0c\u4f7f\u7528<code>type(name, bases, namespace)<\/code><\/li>\n<li><strong>\u81ea\u5b9a\u4e49\u5143\u7c7b\u9700\u8981\u7ee7\u627ftype<\/strong>\uff0c\u5e76\u91cd\u5199<code>__new__<\/code>\u3001<code>__init__<\/code>\u7b49\u65b9\u6cd5<\/li>\n<li><strong>\u5143\u7c7b\u7684\u4f5c\u7528<\/strong>\uff1a\u63a7\u5236\u7c7b\u7684\u521b\u5efa\u8fc7\u7a0b\u3001\u4fee\u6539\u7c7b\u7684\u5c5e\u6027\u548c\u65b9\u6cd5<\/li>\n<li><strong>\u6700\u4f73\u5b9e\u8df5<\/strong>\uff1a\u4ec5\u5728\u9700\u8981\u6df1\u5ea6\u63a7\u5236\u7c7b\u521b\u5efa\u65f6\u4f7f\u7528\uff0c\u4f18\u5148\u8003\u8651\u88c5\u9970\u5668\u3001\u7ee7\u627f\u7b49\u7b80\u5355\u65b9\u6848<\/li>\n<li><strong>\u8c03\u8bd5\u6280\u5de7<\/strong>\uff1a\u4f7f\u7528\u8ffd\u8e2a\u548c\u65e5\u5fd7\u8bb0\u5f55\u6765\u7406\u89e3\u5143\u7c7b\u7684\u6267\u884c\u6d41\u7a0b<\/li>\n<\/ol>\n<h4>\u672a\u6765\u53d1\u5c55<\/h4>\n<p>Python\u7684\u5143\u7c7b\u673a\u5236\u76f8\u5bf9\u7a33\u5b9a\uff0c\u672a\u6765\u7248\u672c\u53ef\u80fd\u4f1a\u5728\u6613\u7528\u6027\u548c\u529f\u80fd\u4e0a\u8fdb\u884c\u6539\u8fdb\uff0c\u4f46\u6838\u5fc3\u6982\u5ff5\u548c\u7528\u6cd5\u4e0d\u4f1a\u6709\u592a\u5927\u53d8\u5316\u3002\u5bf9\u4e8e\u6846\u67b6\u5f00\u53d1\u8005\u548c\u9ad8\u7ea7Python\u7a0b\u5e8f\u5458\u6765\u8bf4\uff0c\u638c\u63e1\u5143\u7c7b\u4ecd\u7136\u662f\u4e00\u9879\u91cd\u8981\u7684\u6280\u80fd\u3002<\/p>\n<p>\u901a\u8fc7\u5408\u7406\u4f7f\u7528\u5143\u7c7b\uff0c\u53ef\u4ee5\u7f16\u5199\u51fa\u66f4\u52a0\u7075\u6d3b\u3001\u5f3a\u5927\u548c\u6613\u4e8e\u7ef4\u62a4\u7684\u4ee3\u7801\uff0c\u7279\u522b\u662f\u5728\u6846\u67b6\u5f00\u53d1\u548c\u590d\u6742\u7cfb\u7edf\u8bbe\u8ba1\u4e2d\u3002\u7136\u800c\uff0c\u8fc7\u5ea6\u4f7f\u7528\u5143\u7c7b\u4f1a\u589e\u52a0\u4ee3\u7801\u7684\u590d\u6742\u6027\u548c\u7406\u89e3\u96be\u5ea6\uff0c\u56e0\u6b64\u9700\u8981\u5728\u529f\u80fd\u9700\u6c42\u548c\u4ee3\u7801\u53ef\u7ef4\u62a4\u6027\u4e4b\u95f4\u627e\u5230\u5e73\u8861\u3002<\/p>\n<p><a href=\"https:\/\/segmentfault.com\/a\/1190000047585270\">https:\/\/segmentfault.com\/a\/1190000047585270<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Python\u4e2d\u7684\u5143\u7c7b\u7f16\u7a0b\u4e0e\u7c7b\u6784\u9020\u673a\u5236\u6df1\u5ea6\u89e3\u6790 1. \u5143\u7c7b\u7684\u57fa\u672c\u6982\u5ff5 1.1 \u4ec0\u4e48\u662f\u5143\u7c7b \u5143\u7c7b\uff08Metaclas [&hellip;]<\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[4],"tags":[],"class_list":["post-10021225","post","type-post","status-publish","format-standard","hentry","category-share"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10021225","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10021225"}],"version-history":[{"count":0,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10021225\/revisions"}],"wp:attachment":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10021225"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10021225"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10021225"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}