python：将正则表达式反向引用值传递给方法

Question

I have this content:

Data1
import filename.in
Data2

and want to replace import filename.in line with the content of filename file, so I use this:

content = re.sub(r'import\s+(.*)\s+\n', '\n' + read_file('\1') + '\n', content)

read_file(in) returns the content of file in .

def read_file(file):
    with open(file) as f:
        return f.read()

the problem is that back-ref \\1 does not eval to filename.in :

No such file or directory: '\\1'

any suggestion?

Answer 1

read_file(..) is called not by the re.sub . '\\1' is used literally as a filename. In addition to that, \\1 is interpreted \\x01 .

To do that you need to pass a replacement function instead:

content = re.sub(
    r'import\s+(.*)\s+\n',
    lambda m: '\n' + read_file(m.group(1)) + '\n',  # `m` is a match object
    content)