django - `**kwargs`和 `**initkwargs`的功能区别

Question

在Django的源码中，有**kwargs和**initkwargs。 django/base.py at master · django/django

class View:

    def __init__(self, **kwargs):
        """
        Constructor. Called in the URLconf; can contain helpful extra
        keyword arguments, and other things.
        """
        # Go through keyword arguments, and either save their values to our
        # instance, or raise an error.
        for key, value in kwargs.items():
            setattr(self, key, value)

和

    @classonlymethod
    def as_view(cls, **initkwargs):
        """Main entry point for a request-response process."""
        for key in initkwargs:
            if key in cls.http_method_names:
                raise TypeError("You tried to pass in the %s method name as a "
                                "keyword argument to %s(). Don't do that."
                                % (key, cls.__name__))

它们在使用上有什么区别？

Answer 1

虽然 kwargs 是约定俗成的名字，但它被称为 initkwargs 的主要原因是为了避免名称冲突:

@classonlymethod
def as_view(cls, **initkwargs):
    """Main entry point for a request-response process."""
    ...

    def view(request, *args, **kwargs):  # defines kwargs
        self = cls(**initkwargs)         # uses initkwargs
        ...
        return self.dispatch(request, *args, **kwargs)
    ...
    return view

请注意，内部 view 函数采用 **kwargs 参数。如果类方法使用相同的名称，内部的 **kwargs 将覆盖外部的 **kwargs，函数将无法访问外部的 kwargs 在实例化 cls 时。

使用名称 initkwargs 可以避免这个问题。