Re: legend and bar?

[John W. Eaton]

On  6-Nov-2007, David Bateman wrote:

| Add an octave_map to base_graphics_object to hold the additional
| arguments and their field name and methods get/set/add/del methods to
| the base class to use these additional arguments. Then you have two
| choices, either all the existing classes for graphics objects can be
| rewritten to use this map for all fields (which would be the
| cleanest),

Doing it this way would make all the individual set_X/get_X functions
somewhat slower as they would have to look up values in the map.

A more important issue (especially when we implement a significant
portion of a graphics backend in C++ instead of in the scripting
language) is that values in the map would all have to have the same
type (presumably octave_value) and I think it would be better for most
of the fixed values to have specific types so that we don't have to
extract the specific types every time we need to get a property value.

I know that currently most properties are stored as octave_value
objects, but this is just temporary, and the goal is to have most of
them stored in more specific types and also to be validated when they
are set.  In many cases, the validation can happen in the constructor
for the specific property type.

| or the get/set methods for each of the graphics objects can hand off to
| the base class for field names it doesn't know rather than returning an
| error, which would be simpler to implement quickly.

I think this would be best, though it is not clear to me whether the
map of properties should be in the base class.  Without looking
closely at it, it seems that each OBJECT::property class should have
its own map to hold user-defined properties, but maybe I'm missing
something about the way the addprops function is supposed to work.

jwe