[cl-pdf-devel] Subclassing charts

[Marc Battyani]

"Jonathon McKitrick" <jcm at FreeBSD-uk.eu.org> wrote:
>
> Suppose I want to subclass a chart, and set some defaults for some slots.
> That seems easy:
>
> (defmethod initialize-instance :after ((chart <my-chart>))
> (setf (slot-value chart 'pdf:title) "My title"))
>
> Fine, no problem.  But what if the slot I want to set is in something not yet
> created, like the legend or axis objects?  How can I force the keyword
> parameters for the internal objects not yet created to be certain default
> values?

All the after methods are called in most-specific-last order. So the :after method of your
subclass is called after the predefined one and the axis objects will be already created.

This is why there are x-axis-options and y-axis-options in charts so that you can pass
specific values for the make-instance of the axis. What is lacking is the ability to pass
the class name to use for these axis but it's rather easy to add.

Marc