## 11.11.3 The Writer Interface

Interfaces to create writers are dependent on the specific writer class being instantiated. The interfaces described below are the required interfaces which all writers must support once initialized. Note that while most applications can use the `AbstractFormatter` class as a formatter, the writer must typically be provided by the application.

`flush` ()
  Flush any buffered output or device control events.

`new_alignment` (align)
  Set the alignment style. The `align` value can be any object, but by convention is a string or `None`, where `None` indicates that the writer's ``preferred'' alignment should be used. Conventional `align` values are `'left'`, `'center'`, `'right'`, and `'justify'`.

`new_font` (font)
  Set the font style. The value of `font` will be `None`, indicating that the device's default font should be used, or a tuple of the form (size, italic, bold, teletype). Size will be a string indicating the size of font that should be used; specific strings and their interpretation must be defined by the application. The italic, bold, and teletype values are boolean indicators specifying which of those font attributes should be used.

`new_margin` (margin, level)
  Set the margin level to the integer `level` and the logical tag to `margin`. Interpretation of the logical tag is at the writer's discretion; the only restriction on the value of the logical tag is that it not be a false value for non-zero values of `level`.

`new_spacing` (spacing)
  Set the spacing style to `spacing`.

`new_styles` (styles)
  Set additional styles. The `styles` value is a tuple of arbitrary values; the value `AS_IS` should be ignored. The `styles` tuple may be interpreted either as a set or as a stack depending on the requirements of the application and writer implementation.

`send_line_break` ()
  Break the current line.

`send_paragraph` (blankline)
  Produce a paragraph separation of at least `blankline` blank lines, or the equivelent. The `blankline` value will be an integer.

`send_hor_rule` (*args, **kw)
  Display a horizontal rule on the output device. The arguments to this method are entirely application- and writer-specific, and should be interpreted with care. The method implementation may assume that a line break has already been issued via `send_line_break()`.

`send_flowing_data` (data)
  Output character data which may be word-wrapped and re-flowed as needed. Within any sequence of calls to this method, the writer may assume that spans of multiple whitespace characters have been collapsed to single space characters.

`send_literal_data` (data)
  Output character data which has already been formatted for display. Generally, this should be interpreted to mean that line breaks indicated by newline characters should be preserved and no new line breaks should be introduced. The data may contain embedded newline and tab characters, unlike data provided to the `send_formatted_data()` interface.

`send_label_data` (data)
  Set `data` to the left of the current left margin, if possible. The value of `data` is not restricted; treatment of non-string values is entirely application- and writer-dependent. This method will only be called at the beginning of a line.