Source code for txaio._iotype

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def guess_stream_needs_encoding(fileobj, default=True):
    """
    Guess the type (bytes/unicode) of this stream, and return whether or not it
    requires text to be encoded before written into it.
    """
    # XXX: Unicode
    # On Python 2, stdout is bytes. However, we can't wrap it in a
    # TextIOWrapper, as it's not from IOBase, so it doesn't have .seekable.
    # It does, however, have a mode, and we can cheese it base on that.
    # On Python 3, stdout is a TextIOWrapper, and so we can safely write
    # str to it, and it will encode it correctly for the target terminal or
    # whatever.
    # If it's a io.BytesIO or StringIO, then it won't have a mode, but it
    # is a read/write stream, so we can get its type by reading 0 bytes and
    # checking the type.
    try:
        # If it's a r/w stream, this will give us the type of it
        t = type(fileobj.read(0))

        if t is bytes:
            return True
        elif t is str:
            return False

    except Exception:
        pass

    try:
        mode = fileobj.mode

        if "b" in mode:
            return True
        else:
            return False
    except Exception:
        pass

    return default