[reportlab-users] How to inherit LinePlot class and add attributes?

[reportlab-users@reportlab.com]

Hi-

I'm working on a time-series line plot.  I want to add an attribute to the
LinePlot class, so I tried to inherit the class and just add a few new
attributes.

However, the whole thing didn't work, as you can tell here:

>>> LinePlot
<class reportlab.graphics.charts.lineplots.LinePlot at 0x00D5B1B0>
>>> class timeseriesLinePlot(LinePlot):
	def __init__(self):
		LinePlot.__init__(self)
		self.startdate = None
		self.enddate = None


>>> ts = timeseriesLinePlot()

Traceback (most recent call last):
  File "<pyshell#42>", line 1, in -toplevel-
    ts = timeseriesLinePlot()
  File "<pyshell#41>", line 4, in __init__
    self.startdate = None
  File "c:\python23\lib\reportlab\graphics\widgetbase.py", line 50, in
__setattr__
    validateSetattr(self,name,value)
  File "c:\python23\lib\reportlab\lib\attrmap.py", line 81, in
validateSetattr
    raise AttributeError, "Illegal attribute '%s' in class %s" % (name,
obj.__class__.__name__)
AttributeError: Illegal attribute 'startdate' in class timeseriesLinePlot
>>>


What am I doing wrong?  I just want to be able to set the start and dates
of my chart. as attributes of the chart itself.

I realize that this probably should occur at the xAxis level, rather than
at the lineplot level, but I'm going to worry about that issue later.