Python 有没有办法让Re.Sub报告它所做的每一次替换

使用matchobj.expand(replacement)，它将处理替换字符串并进行替换:

import re

def replacer2(text, verbose=False):
    def repl(matchobj, replacement):
        result = matchobj.expand(replacement)
        if verbose:
            print(f"Replacing {matchobj.group()} with {result}...")
        return result
    text = re.sub(r"([A-Z]+)(\d+)", lambda m: repl(m, r"\2\1"), text)
    return text

print(replacer2("ABC123", verbose=True)

输出:

Replacing ABC123 with 123ABC...
123ABC

一个带有详细选项的扩展re.sub的通用示例，并允许替换函数使用组模式:

import re

def sub2(pattern, repl, string, count=0, flags=0, verbose=False):
    def helper(match, repl):
        result = match.expand(repl(match) if callable(repl) else repl)
        if verbose:
            print(f'offset {match.start()}: {match.group()!r} -> {result!r}')
        return result
    return re.sub(pattern, lambda m: helper(m, repl), string, count, flags)

# replace three digits with their reverse
print(sub2(r'(\d)(\d)(\d)', r'\3\2\1', 'abc123def45ghi789', verbose=True))
# replace three digits with their reverse, and two digits wrap with parentheses
print(sub2(r'(\d)(\d)(\d)?',
           lambda m: r'(\1\2)' if m.group(3) is None else r'\3\2\1', 
           'abc123def45ghi789', verbose=True))

输出:

offset 3: '123' -> '321'
offset 14: '789' -> '987'
abc321def45ghi987
offset 3: '123' -> '321'
offset 9: '45' -> '(45)'
offset 14: '789' -> '987'
abc321def(45)ghi987