python - 使用 with - python 打开超过 1 个文件

Question

通常，我们会用它来读/写文件:

with open(infile,'r') as fin:
  pass
with open(outfile,'w') as fout:
  pass

要读取一个文件并输出到另一个文件，我可以只用一个 with 来完成吗？

我一直这样做:

with open(outfile,'w') as fout:
  with open(infile,'r') as fin:
    fout.write(fin.read())

有没有像下面这样的东西，(虽然下面的代码不起作用):

with open(infile,'r'), open(outfile,'w') as fin, fout:
  fout.write(fin.read())

使用一个 with 而不是多个 with 有什么好处吗？是否有一些 PEP 讨论了这个问题？

Answer 1

with open(infile,'r') as fin, open(outfile,'w') as fout:
   fout.write(fin.read()) 

以前必须使用(现已弃用)contextlib.nested , 但从 Python2.7 开始，with supports multiple context managers .