[Safe repr] safe recursive repr function #python

safe_repr.py

# https://blog.ionelmc.ro/2020/01/20/is-there-anything-safe-in-python/

def safe_repr(obj, maxdepth=5):
    if not maxdepth:
        return '...'
    obj_type = type(obj)
    obj_type_type = type(obj_type)
    newdepth = maxdepth - 1

    # only represent exact builtins
    # (subclasses can have side-effects due to __class__ being
    # a property, __instancecheck__, __subclasscheck__ etc)
    if obj_type is dict:
        return '{%s}' % ', '.join('%s: %s' % (
            safe_repr(k, maxdepth),
            safe_repr(v, newdepth)
        ) for k, v in obj.items())
    elif obj_type is list:
        return '[%s]' % ', '.join(
            safe_repr(i, newdepth) for i in obj
        )
    elif obj_type is tuple:
        return '(%s%s)' % (
            ', '.join(safe_repr(i, newdepth) for i in obj),
            ',' if len(obj) == 1 else ''
        )
    elif obj_type is set:
        return '{%s}' % ', '.join(
            safe_repr(i, newdepth) for i in obj
        )
    elif obj_type is frozenset:
        return '%s({%s})' % (
            obj_type.__name__,
            ', '.join(safe_repr(i, newdepth) for i in obj)
        )
    elif obj_type is deque:
        return '%s([%s])' % (
            obj_type.__name__, ', '.join(safe_repr(i, newdepth) for i in obj)
        )
    elif obj_type in (Counter, OrderedDict, defaultdict):
        return '%s({%s})' % (
            obj_type.__name__,
            ', '.join('%s: %s' % (
                safe_repr(k, maxdepth),
                safe_repr(v, newdepth)
            ) for k, v in obj.items())
        )
    elif obj_type is types.MethodType:  # noqa
        self = obj.__self__
        name = getattr(obj, '__qualname__', None)
        if name is None:
            name = obj.__name__
        return '<%sbound method %s of %s>' % (
            'un' if self is None else '',
            name,
            safe_repr(self, newdepth)
        )
    elif obj_type_type is type and BaseException in obj_type.__mro__:
        return '%s(%s)' % (
            obj_type.__name__,
            ', '.join(safe_repr(i, newdepth) for i in obj.args)
        )
    elif obj_type_type is type and \
         obj_type is not InstanceType and \
         obj_type.__module__ in (builtins.__name__, 'io', 'socket', '_socket'):
        # hardcoded list of safe things. note that isinstance ain't used
        # (and we don't trust subclasses to do the right thing in __repr__)
        return repr(obj)
    else:
        return object.__repr__(obj)