为什么将不正确的输出附加到我的python文件中？

问题描述

我有python文件试图在此处修改其他python文件：

file = "PythonFile1.py"

with open(file,"r") as current_file:
    lines = current_file.readlines()
for line in lines:
    if line != 'sys.stdout = open("test.txt","w")' or line != "sys.stdout.close()" or line != "import sys":
        del lines[lines.index(line)]
with open(file,"w") as current_file:
    for line in lines:
        current_file.write(line)

print(lines)

这是试图修改的python文件：

import sys
sys.stdout = open("test.txt","w")
sys.stdout.close()

当我运行第一个python文件时，我在另一个python文件中得到了这个结果。

sys.stdout = open("test.txt","w")

我正在寻找文件内容为

import sys
sys.stdout = open("test.txt","w")
sys.stdout.close()

我不确定为什么它没有赶上我想留下的界限，任何人都可以帮助解决此问题吗？

解决方法

with open(file,"w") as current_file:
    current_file.write('\n'.join(lines))

您不需要遍历它并编写它们，只需加入代码行并直接编写一次即可。循环时，每次循环都将替换文件中已存在的内容，除非您使用附加模式。将这些行连接在一起并直接编写它们会更容易。

---

Read more about the join method

,

这就是我要做的：

magic_lines = [
    "sys.stdout = open('test.txt','w')","sys.stdout.close()","import sys"
]

with open(infilepath,'r') as infile:
    lines = infile.readlines()

with open(infilepath,'w') as outfile:
    for line in lines:
        if line.strip() in magic_lines:
            outfile.write(line)

但是在我看来，您可以nuke并完全铺平文件：

from textwraps import dedent

with open(infilepath,'w') as infile:
    infile.write(dedent("""\
        import sys
        sys.stdout = open("test.txt","w")
        sys.stdout.close()
    """))