Python 中的 Agrv 需要多个值才能解包？

Question

我一直在关注 Zed A. Shaw 的 "Learn Python the Hard Way" 这本书。我目前在练习 18，从练习 16 开始就遇到这个问题。我的代码是这样的：

from sys import argv
from os.path import exists

script, from_file, to_file = argv

print "Copying from %s to %s" % (from_file, to_file)

# we could do these two on one line, how?
in_file = open(from_file)
indata = in_file.read()

print "The input file is %d bytes long %r" % len(indata)
print "Ready, hit RETURN to continues, CTRL-C to abort."
raw_input()

out_file = open(to_file, 'w')
out_file.write(indata)

print "Alright, all done."

out_file.close()
in_file.close()

终端 (macOS) 中的结果是：

Traceback (most recent call last):
File "ex17.py", line 4, in <module>
script, from_file, to_file = argv
ValueError: need more than 2 values to unpack

我正在使用 macOS High Serria，使用 Python 2.7（非内置）在 Atom 中编码。

谢谢！

Answer 1

script, from_file, to_file = argv

这一行意味着它应该接受来自运行命令的三个值：

python test.py FileA FileB

您的脚本 test.py from_file 是 FileA 并且 to_file 是 FileB

Python 中的 Agrv 需要多个值才能解包？

Agrv in Python Needs More Than One Value to Unpack?

python

python-2.7

argv