In python when passing arguments what does ** before an argument do?
本问题已经有最佳答案，请猛点这里访问。
Possible Duplicate:
What does *args and **kwargs mean?
从阅读这个例子和我对python的微薄了解来看，它一定是将数组转换为字典或其他东西的快捷方式。
1 2 3 4 5 | class hello: def GET(self, name): return render.hello(name=name) # Another way: #return render.hello(**locals()) |
在python中，
举个例子：
1 2 3 | def f(count, msg): for i in range(count): print msg |
使用
1 2 3 4 5 6 7 | >>> d = {'count': 2, 'msg':"abc"} >>> f(**d) abc abc >>> a = [1,"xyz"] >>> f(*a) xyz |
**local()传递与调用方的本地命名空间相对应的字典。当传递带有**的函数时，将传递字典，这将允许可变长度参数列表。
从python文档5.3.4：
If any keyword argument does not correspond to a formal parameter name, a TypeError exception is raised, unless a formal parameter using the syntax **identifier is present; in this case, that formal parameter receives a dictionary containing the excess keyword arguments (using the keywords as keys and the argument values as corresponding values), or a (new) empty dictionary if there were no excess keyword arguments.
在不同的上下文中，这也用于电源运算符。
它将字典"解包"为参数列表。IE：
1 2 | def somefunction(keyword1, anotherkeyword): pass |
它可以被称为
1 2 3 4 | somefunction(keyword1=something, anotherkeyword=something) or as di = {'keyword1' : 'something', anotherkeyword : 'something'} somefunction(**di) |