Class StringIO

Lib/_pyio.py:2730–2778

Text I/O implementation using an in-memory buffer. The initial_value argument sets the value of object. The newline argument is like the one of TextIOWrapper's constructor.

class StringIO(TextIOWrapper):
    """Text I/O implementation using an in-memory buffer.

    The initial_value argument sets the value of object.  The newline
    argument is like the one of TextIOWrapper's constructor.
    """

    def __init__(self, initial_value="", newline="\n"):
        super(StringIO, self).__init__(BytesIO(),
                                       encoding="utf-8",
                                       errors="surrogatepass",
                                       newline=newline)
        # Issue #5645: make universal newlines semantics the same as in the
        # C version, even under Windows.
        if newline is None:
            self._writetranslate = False
        if initial_value is not None:
            if not isinstance(initial_value, str):
                raise TypeError("initial_value must be str or None, not {0}"
                                .format(type(initial_value).__name__))
            self.write(initial_value)
            self.seek(0)

    def getvalue(self):
        self.flush()
        decoder = self._decoder or self._get_decoder()
        old_state = decoder.getstate()
        decoder.reset()
        try:
            return decoder.decode(self.buffer.getvalue(), final=True)
        finally:
            decoder.setstate(old_state)

    def __repr__(self):
        # TextIOWrapper tells the encoding in its repr. In StringIO,
        # that's an implementation detail.
        return object.__repr__(self)

    @property
    def errors(self):
        return None

    @property
    def encoding(self):
        return None

    def detach(self):
        # This doesn't make sense on StringIO.
        self._unsupported("detach")