File objects don't have a writable name attribute, so the IO stub seems reasonable. What seems to be going on is that StringIO does not fully implement the IO interface, but we declare it as a subclass of IO for convenience, since in most respects it acts like an IO object.

A somewhat correct fix would be to 'undefine' name in StringIO, but there's no standard way to do that. Defining it as a regular attribute seems like a lie, if it actually isn't defined. You can assign to an arbitrary attribute such as asdfasdf and Python will not complain. We want to be able to catch assignments to undefined attributes.

My suggestion is to use setattr to set the attribute, or to cast the StringIO object to Any before performing the manipulations, as this feels like something a type checker can't easily support without allowing genuinely bad code to pass type checking. But perhaps this is special and I'm missing something?

For now I'm using this workaround in zulip's code:

from six.moves import StringIO as _StringIO
class StringIO(_StringIO):
    name = ''

I have a similar issuee. What I'm trying to do is treat a cx_Oracle.CLOB value like a stream (which seems quite natural, only the LOB API is a bit different).

My attempt is like this:

class UnbufferedClobReader(io.TextIOBase):
    """
    A file-like wrapper for a read-only cx_Oracle CLOB object.
    """
    def __init__(self, clobLocator, encoding):
        self.clobLocator = clobLocator
        self.offset = 0
        self.encoding = encoding
        self.size = clobLocator.size()
        log.debug("CLOB reader created, size=%s", self.size)

    def seekable(self):
        return True
    
    def seek(self, offset, whence):
        log.debug("CLOB seek: offset=%s, whence=%r", offset, whence)
        if whence == 0:
            self.offset = offset
        elif whence == 1:
            self.offset += offset
            if self.offset < 0:
                self.offset = 0
        elif whence == 2:
            if offset <= 0 and -offset <= self.size:
                self.offset = self.size + offset
            else:
                raise IOError(96, "Invalid offset for CBlobReader")
        else:
            self._unsupported("seek")
        return self.offset

    def readable(self):
        return True
        
    def read(self, size):
        size = min(self.size - self.offset, size)
        log.debug("CLOB read %s chars at offset %s", size, self.offset)
        if size == 0:
            return ""
        chunk = self.clobLocator.read(self.offset + 1, size)
        assert len(chunk) == size
        self.offset += size
        return chunk

Note: Actually I only need the read method in my code.

The constructor fails with the exception
AttributeError: attribute 'encoding' of '_io._TextIOBase' objects is not writable

Having non-writable attributes seems somewhat un-pythonic to me.
Any ideas how specifying the encoding (for when the stream has to be written to a byte stream) can be accomplished?