python3偶尔会在换行时拆分argv

Question

太长了，读不下去了，Python 3在奇怪的地方偶尔会分裂{{CD1}}，不像Python 2。你知道吗

讨论最初是在on the Git mailing list开始的。在短暂的谷歌搜索之后，我找不到任何关于这个主题的文档。你知道吗

print_argv.py：

import sys
from pprint import pprint

pprint(sys.argv)

test.py：

import sys
import subprocess

subprocess.check_call([
    'python%s' % sys.argv[1],
    './print_argv.py',
    'similarity index 90%\nrename from file1.txt\nrename to file1-mv.txt\nindex 2bef330..f8fd673 100644\n',
])

Python 2，预期行为：

$ python3 test.py 2
['./print_argv.py',
 'similarity index 90%\nrename from file1.txt\nrename to file1-mv.txt\nindex 2bef330..f8fd673 100644\n']

Python 3，破坏行为：

$ python3 test.py 3
['./print_argv.py',
 'similarity index 90%\n'
 'rename from file1.txt\n'
 'rename to file1-mv.txt\n'
 'index 2bef330..f8fd673 100644\n']

直接通过shell实现。Python 2，预期行为：

$ python2 print_argv.py 'similarity index 90%\nrename from file1.txt\nrename to file1-mv.txt\nindex 2bef330..f8fd673 100644\n'
['print_argv.py',
 'similarity index 90%\\nrename from file1.txt\\nrename to file1-mv.txt\\nindex 2bef330..f8fd673 100644\\n']

Python3，非常坏的行为：

$ python3 print_argv.py 'similarity index 90%\nrename from file1.txt\nrename to file1-mv.txt\nindex 2bef330..f8fd673 100644\n'
['print_argv.py',
 'similarity index 90%\\nrename from file1.txt\\nrename to '
 'file1-mv.txt\\nindex 2bef330..f8fd673 100644\\n']

这种分裂行为是错误吗？你知道吗

Answer 1

我已经弄明白了。这不是bug，而是pprint()的特性。它分割字符串以避免长行，并且滥用了在Python中用空格分割的字符串由解析器连接的事实。你知道吗

另外，在我的示例中，换行符在shell中没有正确解析。逃离它们，我得到与subprocess.check_call()中完全相同的行为：

$ python2 print_argv.py $'similarity index 90%\nrename from file1.txt\nrename to file1-mv.txt\nindex 2bef330..f8fd673 100644\n'
['print_argv.py',
 'similarity index 90%\nrename from file1.txt\nrename to file1-mv.txt\nindex 2bef330..f8fd673 100644\n']
$ python3 print_argv.py $'similarity index 90%\nrename from file1.txt\nrename to file1-mv.txt\nindex 2bef330..f8fd673 100644\n'
['print_argv.py',
 'similarity index 90%\n'
 'rename from file1.txt\n'
 'rename to file1-mv.txt\n'
 'index 2bef330..f8fd673 100644\n']

一个关于同一主题的问题：Can I make pprint in python3 not split strings, like in python2?