python，如何批量创建类？

python, how to batch create class?

我是Python的新手，我想创建3个类，如下所示：

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class ProtectTemplate(TemplateView):
@method_decorator(login_required)
def dispatch(self, *args, **kwargs):
return super(ProtectTemplate, self).dispatch(*args, **kwargs)

def get_context_data(self, **kwargs):
context['phone'] = xxx
return context

class ProtectList(ListView):
@method_decorator(login_required)
def dispatch(self, *args, **kwargs):
return super(ProtectList, self).dispatch(*args, **kwargs)

def get_context_data(self, **kwargs):
context['phone'] = xxx
return context

class ProtectDetail(DetailView):
@method_decorator(login_required)
def dispatch(self, *args, **kwargs):
return super(ProtectDetail, self).dispatch(*args, **kwargs)

def get_context_data(self, **kwargs):
context['phone'] = xxx
return context

我觉得很糟糕。所以我试着这样做：

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login_class = [
('ProtectTemplate', TemplateView),
('ProtectList', ListView),
('ProtectDetail', DetailView),
]

for c, v in login_class:
class c(v):
@method_decorator(login_required)
def dispatch(self, *args, **kwargs):
return super(self.__class__, self).dispatch(*args, **kwargs)

def get_context_data(self, **kwargs):
context['phone'] = xxx
return context

但它不起作用。是否仍要批量创建3类？

相关讨论

您的循环是正确的方法，但是您正在重新绑定c(而不是为类设置新的全局名称)，您不能在class语句中使用变量来命名类(该类将被称为c，使用super(self.__class__, self)将导致无限的递归问题。

您可以使用工厂函数，然后使用globals()字典将新创建的类添加到全局命名空间。函数提供了一个闭包，因此我们可以将实际类对象传递给super()：

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def _create_login_class(name, base):
class LoginCls(base):
@method_decorator(login_required)
def dispatch(self, *args, **kwargs):
return super(LoginCls, self).dispatch(*args, **kwargs)

def get_context_data(self, **kwargs):
context['phone'] = xxx
return context

LoginCls.__name__ = name
LoginCls.__qualname__ = name # Python 3
return LoginCls

_login_class = [
('ProtectTemplate', TemplateView),
('ProtectList', ListView),
('ProtectDetail', DetailView),
]

for _name, _base in _login_class:
globals()[_name] = _create_login_class(_name, _base)

super(LoginCls, self)表达式在父函数命名空间中查找LoginCls作为非本地名称，因此始终使用正确的上下文来查找mro中的下一个类。

我使用了前导下划线名称来表示工厂函数和_login_class、_name和_base名称是模块的实现细节。

演示：

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>>> class Base:
... def dispatch(self, *args, **kwargs): print('Base.dispatch({}, {}) called'.format(args, kwargs))
...
>>> class TemplateView(Base): pass
...
>>> class ListView(Base): pass
...
>>> class DetailView(Base): pass
...
>>> method_decorator = lambda *args: lambda f: f
>>> xxx = 'xxx'
>>> login_required = 'login_required'
>>> def _create_login_class(name, base):
... class LoginCls(base):
... @method_decorator(login_required)
... def dispatch(self, *args, **kwargs):
... return super(LoginCls, self).dispatch(*args, **kwargs)
... def get_context_data(self, **kwargs):
... context['phone'] = xxx
... return context
... LoginCls.__name__ = name
... LoginCls.__qualname__ = name # Python 3
... return LoginCls
...
>>> _login_class = [
... ('ProtectTemplate', TemplateView),
... ('ProtectList', ListView),
... ('ProtectDetail', DetailView),
... ]
>>> for _name, _base in _login_class:
... globals()[_name] = _create_login_class(_name, _base)
...
>>> ProtectTemplate
<class '__main__.ProtectTemplate'>
>>> class SubclassDemo(ProtectTemplate):
... def dispatch(self, *args, **kwargs):
... print('SubclassDemo.dispatch({}, {}) called'.format(args, kwargs))
... super(SubclassDemo, self).dispatch(*args, **kwargs)
...
>>> SubclassDemo().dispatch(42, spam='ham')
SubclassDemo.dispatch((42,), {'spam': 'ham'}) called
Base.dispatch((42,), {'spam': 'ham'}) called