How to solve this inheritance problem in Python?

Question

Python

I need to redefine the config parser so that when an exception occurs, the configparser.DuplicateOptionError program simply writes a warning to the logs and continues to work. I wrote this code:

import configparser


class CustomConfigParser(configparser.ConfigParser):
    def __init__(self, logger, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.logger = logger

    def _read(self, *args, **kwargs):
        try:
            super()._read(*args, **kwargs)
        except configparser.DuplicateOptionError as error:
            self.logger.warning(error)
            # тут теоритически должен быть continue, но поскольку мы используем super() - 
            # это не будет работать

Here is the method code in python sources

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.
        """
        elements_added = set()
        cursect = None                        # None, or a dictionary
        sectname = None
        optname = None
        lineno = 0
        indent_level = 0
        e = None                              # None, or an exception
        for lineno, line in enumerate(fp, start=1):
            comment_start = sys.maxsize
            # strip inline comments
            inline_prefixes = {p: -1 for p in self._inline_comment_prefixes}
            while comment_start == sys.maxsize and inline_prefixes:
                next_prefixes = {}
                for prefix, index in inline_prefixes.items():
                    index = line.find(prefix, index+1)
                    if index == -1:
                        continue
                    next_prefixes[prefix] = index
                    if index == 0 or (index > 0 and line[index-1].isspace()):
                        comment_start = min(comment_start, index)
                inline_prefixes = next_prefixes
            # strip full line comments
            for prefix in self._comment_prefixes:
                if line.strip().startswith(prefix):
                    comment_start = 0
                    break
            if comment_start == sys.maxsize:
                comment_start = None
            value = line[:comment_start].strip()
            if not value:
                if self._empty_lines_in_values:
                    # add empty line to the value, but only if there was no
                    # comment on the line
                    if (comment_start is None and
                        cursect is not None and
                        optname and
                        cursect[optname] is not None):
                        cursect[optname].append('') # newlines added at join
                else:
                    # empty line marks end of value
                    indent_level = sys.maxsize
                continue
            # continuation line?
            first_nonspace = self.NONSPACECRE.search(line)
            cur_indent_level = first_nonspace.start() if first_nonspace else 0
            if (cursect is not None and optname and
                cur_indent_level > indent_level):
                cursect[optname].append(value)
            # a section header or option header?
            else:
                indent_level = cur_indent_level
                # is it a section header?
                mo = self.SECTCRE.match(value)
                if mo:
                    sectname = mo.group('header')
                    if sectname in self._sections:
                        if self._strict and sectname in elements_added:
                            raise DuplicateSectionError(sectname, fpname,
                                                        lineno)
                        cursect = self._sections[sectname]
                        elements_added.add(sectname)
                    elif sectname == self.default_section:
                        cursect = self._defaults
                    else:
                        cursect = self._dict()
                        self._sections[sectname] = cursect
                        self._proxies[sectname] = SectionProxy(self, sectname)
                        elements_added.add(sectname)
                    # So sections can't start with a continuation line
                    optname = None
                # no section header in the file?
                elif cursect is None:
                    raise MissingSectionHeaderError(fpname, lineno, line)
                # an option line?
                else:
                    mo = self._optcre.match(value)
                    if mo:
                        optname, vi, optval = mo.group('option', 'vi', 'value')
                        if not optname:
                            e = self._handle_error(e, fpname, lineno, line)
                        optname = self.optionxform(optname.rstrip())
                        if (self._strict and
                            (sectname, optname) in elements_added):
                            raise DuplicateOptionError(sectname, optname,
                                                       fpname, lineno)
                        elements_added.add((sectname, optname))
                        # This check is fine because the OPTCRE cannot
                        # match if it would set optval to None
                        if optval is not None:
                            optval = optval.strip()
                            cursect[optname] = [optval]
                        else:
                            # valueless option handling
                            cursect[optname] = None
                    else:
                        # a non-fatal parsing error occurred. set up the
                        # exception but keep going. the exception will be
                        # raised at the end of the file and will contain a
                        # list of all bogus lines
                        e = self._handle_error(e, fpname, lineno, line)
        self._join_multiline_values()
        # if any parsing errors occurred, raise an exception
        if e:
            raise e

Is there a way to do something like this without copying the whole method from configparse.py?

Answer 1

Nifiga. There is no way to continue outside. The Italian wrote the code - not otherwise. Spaghetti obviously with cheese.
But you have the opportunity to fork and refactor this parser, although it would be better to just take another good one, even if not from the standard library.
This, of course, is a python, and you can write a decorator that will fix the bytecode, but for this, it seems to me, you have to burn forever in the hell of cyclic binary dependencies.
Oh, well, another idea on the verge of a foul. Try to override _strict with a property, and initiate warning on the getter. True, you will never know on which double the problem is. And also, in order not to get confused in case of irrelevant calls to _strinct, you can turn on the warning mode and turn it off before and after the overridden method. Such a dirty hack based on side effects.
You can fix the _strict parameter and the error will not be triggered, but you will be left without warning.