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.
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'.
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.
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.
spacing.
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.
blankline blank
lines, or the equivelent. The blankline value will be an
integer.
send_line_break().
send_formatted_data() interface.
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.