IndexError: tuple index out of range when parsing method arguments

Question

我已经检查了 this 个问题，但找不到答案。这是一个演示我的用例的简单示例：

def log(*args):
    message = str(args[0])
    arguments = tuple(args[1:])
    # message itself
    print(message)
    # arguments for str.format()0
    print(arguments)
    # shows that arguments have correct indexes
    for index, value in enumerate(arguments):
        print("{}: {}".format(index, value))
    # and amount of placeholders == amount of arguments
    print("Amount of placeholders: {}, Amount of variables: {}".format(message.count('{}'), len(arguments)))

    # But this still fails! Why?
    print(message.format(arguments))

log("First: {}, Second: {}, Third: {}, Fourth: {}", "asdasd", "ddsdd", "12312333", "fdfdf")

并且输出：

First: {}, Second: {}, Third: {}, Fourth: {}
('asdasd', 'ddsdd', '12312333', 'fdfdf')
0: asdasd
1: ddsdd
2: 12312333
3: fdfdf
Amount of placeholders: 4, Amount of variables: 4
Traceback (most recent call last):
  File "C:/Users/sbt-anikeev-ae/IdeaProjects/test-this-thing-on-python/test-this-thing.py", line 12, in <module>
    log("First: {}, Second: {}, Third: {}, Fourth: {}", "asdasd", "ddsdd", "12312333", "fdfdf")
  File "C:/Users/sbt-anikeev-ae/IdeaProjects/test-this-thing-on-python/test-this-thing.py", line 10, in log
    print(message.format(arguments))
IndexError: tuple index out of range

P.S: 我已经拒绝使用这种方法（包装 str.format()），因为它似乎是多余的。但是还是很疑惑，为什么没有达到预期的效果呢？

Answer 1

您必须使用 * 将元组解压为 format:

的实际参数

print(message.format(*arguments))

否则，arguments 被视为 format 的唯一参数（它适用于第一个 {} 出现，通过将你的元组转换为字符串，但是当它遇到第二次出现时窒息{})

Answer 2

您需要传递参数而不是元组。这是通过使用“*arguments”来完成的。 Expanding tuples into arguments

def log(*args):
    message = str(args[0])
    arguments = tuple(args[1:])
    # message itself
    print(message)
    # arguments for str.format()0
    print(arguments)
    # shows that arguments have correct indexes
    for index, value in enumerate(arguments):
        print("{}: {}".format(index, value))
    # and amount of placeholders == amount of arguments
    print("Amount of placeholders: {}, Amount of variables: {}".format(message.count('{}'), len(arguments)))

    # But this still fails! Why?
    print(type(arguments))
    print(message.format(*arguments))

log("First: {}, Second: {}, Third: {}, Fourth: {}", "asdasd", "ddsdd", "12312333", "fdfdf")

Answer 3

试试这个

print(message.format(*arguments))

format 不期望元组

IndexError: tuple index out of range when parsing method arguments

IndexError: tuple index out of range when parsing method arguments

python

string-formatting