来自文档：
回写配置时，不会保留原始配置文件中的注解。

• • IF注解总是**在节名之前，您可以对文件进行预处理和后处理，以捕获注解并在更改后恢复它们。这有点像黑客，但可能比扩展configparser.ConfigParser更容易实现。

不考虑行内注解，尽管可以使用相同的方法来查找、关联和恢复行内注解。
使用正则表达式查找注解，然后将其与节关联。

import configparser as cp
import re

pattern = r'([#;][^[]*)(\[[^]]*\])'
rex = re.compile(pattern)
# {section_name:comment}
comments = {}
with open('test.ini') as f:
    text = f.read()
for comment,section in rex.findall(text):
    comments[section] = comment

使用ConfigParser进行更改。

parser: cp.ConfigParser = cp.ConfigParser()
parser.read("test.ini")

parser.set("My-Section", "New-Test_option", "TEST")

with open("test.ini", "w") as configfile:
    parser.write(configfile)

恢复注解。

with open('test.ini') as f:
    text = f.read()
for section,comment in comments.items():
    text = text.replace(section,comment+section)
with open('test.ini','w') as f:
    f.write(text)

test.ini

# comment line
; other comment line
[My-Section]
test-option = Test-Variable

; another pesky comment

[foo-section]
this-option = x

comments命令如下所示：

{'[My-Section]': '# comment line\n; other comment line\n',
 '[foo-section]': '; another pesky comment\n\n'}

更改后的test.ini

# comment line
; other comment line
[My-Section]
test-option = Test-Variable
new-test_option = TEST

; another pesky comment

[foo-section]
this-option = x

最后，这里是ConfigParser的一个子类，重写了_read和_write_section方法，以便查找/关联/恢复注解如果它们 * 出现 * 在节之前。

import configparser as cp
from configparser import *
import re
class ConfigParserExt(cp.ConfigParser):
    def _read(self, fp, fpname):
        """Parse a sectioned configuration file.
        Each section in a configuration file contains a header, indicated by
        a name in square brackets (`[]`), plus key/value options, indicated by
        `name` and `value` delimited with a specific substring (`=` or `:` by
        default).
        Values can span multiple lines, as long as they are indented deeper
        than the first line of the value. Depending on the parser's mode, blank
        lines may be treated as parts of multiline values or ignored.
        Configuration files may include comments, prefixed by specific
        characters (`#` and `;` by default). Comments may appear on their own
        in an otherwise empty line or may be entered in lines holding values or
        section names. Please note that comments get stripped off when reading configuration files;
        unless they are positioned just before sections
        """

        # find comments and associate with section
        try:
            text = fp.read()
            fp.seek(0)
        except AttributeError as e:
            text = ''.join(line for line in fp)
        rex = re.compile(r'([#;][^[]*)(\[[^]]*\])')
        self.preserved_comments = {}
        for comment,section in rex.findall(text):
            self.preserved_comments[section] = comment
        
        super()._read(fp,fpname)

    def _write_section(self, fp, section_name, section_items, delimiter):
        """Write a single section to the specified `fp`."""
        # restore comment to section
        if f'[{section_name}]' in self.preserved_comments:
            fp.write(self.preserved_comments[f'[{section_name}]'])
        super()._write_section( fp, section_name, section_items, delimiter)