当与形式(position)、*args和**kwargs一起使用时，显式传递命名（关键字）参数

Question

#!/usr/bin/python

import sys
import os

from pprint import pprint as pp

def test_var_args(farg, default=1, *args, **kwargs):
    print "type of args is", type(args)
    print "type of args is", type(kwargs)

    print "formal arg:", farg
    print "default arg:", default

    for arg in args:
        print "another arg:", arg

    for key in kwargs:
        print "another keyword arg: %s: %s" % (key, kwargs[key])

    print "last argument from args:", args[-1]


test_var_args(1, "two", 3, 4, myarg2="two", myarg3=3)

type of args is <type 'tuple'>
type of args is <type 'dict'>
formal arg: 1
default arg: two
another arg: 3
another arg: 4
another keyword arg: myarg2: two
another keyword arg: myarg3: 3
last argument from args: 4

type of args is <type 'tuple'>
type of args is <type 'dict'>
formal arg: 1
default arg: 1
another arg: two
another arg: 3
another arg: 4
another keyword arg: myarg2: two
another keyword arg: myarg3: 3
last argument from args: 4

type of args is <type 'tuple'>
type of args is <type 'dict'>
formal arg: 1
default arg: two
another arg: 3
another arg: 4
another keyword arg: myarg2: two
another keyword arg: myarg3: 3
last argument from args: 4

我尝试了以下内容，但它也返回编译错误:test_var_args(1,3,4,myarg2=“two”,myarg3=3)

这可能吗？

Answer 1

不幸的是，我认为那是不可能的。

正如萨姆指出的，你可以通过从Kwargs中取出值来实现同样的行为。如果逻辑依赖于kwargs不包含“default”参数，则可以使用pop方法将其从kwargs字典中删除（参见此处）。以下代码的行为与您所需的类似：

import sys
import os

from pprint import pprint as pp

def test_var_args(farg, *args, **kwargs):
    print "type of args is", type(args)
    print "type of args is", type(kwargs)

    print "formal arg:", farg
    print 'default', kwargs.pop('default', 1)

    for arg in args:
        print "another arg:", arg

    for key in kwargs:
        print "another keyword arg: %s: %s" % (key, kwargs[key])

    print "last argument from args:", args[-1]

# Sample call
test_var_args(1, 3, 4, default="two", myarg2="two", myarg3=3)

它的工作原理与你在问题中想要的类似