Python 向调用方命名空间添加动态类 问题

无法在函数中动态创建具有本地作用域的类，但可以在顶级工作

问题: 如何在正确的命名空间范围内动态创建类

---

我试图动态创建添加到调用方命名空间的类

这样我就能做到以下几点

import creator
creator.make('SomeClass')
print "SomeClass :", SomeClass

当在顶层添加动态类时，这可以起作用，但是当尝试在函数中执行相同操作时，这样创建的类只有局部作用域，它就不起作用了

我看到有一个放在函数中可以工作，但它会消失

下面的代码显示了这个问题，显然，

creator.py

的问题比上面显示的要多

# creator.py    
import inspect

def make(classname):
    t = type(classname, (object,), { })
    frame = inspect.currentframe()
    print "WILL make() - callers locals :", frame.f_back.f_locals.keys()
    frame.f_back.f_locals[classname] = t
    print "DID  make() - callers locals :", frame.f_back.f_locals.keys()
    return t

---

输出：

WILL __main__ - locals : ['creator', '__builtins__', '__file__', '__package__', '__name__', '__doc__']
WILL make() - callers locals : ['creator', '__builtins__', '__file__', '__package__', '__name__', '__doc__']
DID  make() - callers locals : ['creator', '__builtins__', 'SomeClass', '__file__', '__package__', '__name__', '__doc__']
DID  __main__ - locals : ['creator', '__builtins__', 'SomeClass', '__file__', '__package__', '__name__', '__doc__']
SomeClass : <class 'creator.SomeClass'>
--------------------------------------------------------------------------------
WILL closed() - locals : ['ClosedClass']
WILL make() - callers locals : ['ClosedClass']
DID  make() - callers locals : ['ClosedClass', 'AnotherClass']
DID  closed() - locals : ['ClosedClass', 'AnotherClass']
OUCH: global name 'AnotherClass' is not defined

WILL\uuuuu main\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu
WILL make（）-调用者局部变量：['creator'，'uuuuu内置项'，'uuuu文件'，'uuuuu包'，'uuuuu名称'，'uuuu文档']
DID make（）-调用者局部变量：['creator'，'uuuuu内置项'，'SomeClass'，'uuuu文件'，'uuuu包'，'uuuu名称'，'uuuu文档']
DID uuu main uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu
某类：
--------------------------------------------------------------------------------
WILL closed（）-locals:['ClosedClass']
将使（）调用方成为本地人：['ClosedClass']
DID make（）-调用方本地：['ClosedClass'，'AnotherClass']
DID closed（）-局部变量：['ClosedClass'，'AnotherClass']
哎哟：未定义全局名称“AnotherClass”

当然我不想要

哎哟：…

查看

locals（）

中的

closed

可以想象它应该可以工作，但是正如在hack中提到的，Python编译器正在优化局部变量，而没有引入新的动态局部变量

如果我取消注释

exec'

行，它就会工作

我可以用全局范围创建这些类，但我正在努力保持名称空间的干净

我当然可以做

AnotherClass=creator.make（'AnotherClass'）

，但我正在努力保持干燥

有没有办法让它在没有

exec'

hack的情况下工作

还是要让它们全球化？

不。访问局部变量的唯一方法是通过或

vars（）

，在这两种情况下，文档都明确指出，不能保证对

dict

返回的修改会影响局部变量，因此：无法可靠地做到这一点

如果您希望静态修改局部变量，那么您可能可以修改与函数关联的代码对象以提供更多的局部变量，但这可能不可能，或者很难可靠地完成，我认为没有理由这样做

WILL __main__ - locals : ['creator', '__builtins__', '__file__', '__package__', '__name__', '__doc__']
WILL make() - callers locals : ['creator', '__builtins__', '__file__', '__package__', '__name__', '__doc__']
DID  make() - callers locals : ['creator', '__builtins__', 'SomeClass', '__file__', '__package__', '__name__', '__doc__']
DID  __main__ - locals : ['creator', '__builtins__', 'SomeClass', '__file__', '__package__', '__name__', '__doc__']
SomeClass : <class 'creator.SomeClass'>
--------------------------------------------------------------------------------
WILL closed() - locals : ['ClosedClass']
WILL make() - callers locals : ['ClosedClass']
DID  make() - callers locals : ['ClosedClass', 'AnotherClass']
DID  closed() - locals : ['ClosedClass', 'AnotherClass']
OUCH: global name 'AnotherClass' is not defined