Builtin variables [was Re: Bug#182000]

[Paul Kienzle]

John W. Eaton wrote:

> Finally, what if we had a way to install built-in variables in the
> scripting language?  Then we could move things like the initialization
> of things like octave_config_info out of the C++ code and into the
> startup files.
I'm in favour of doing as much as possible in m-files,
and doing anything from outside octave that can be
done in octave.

Built-in variables are a little bit strange in that they
appear automatically in every scope.  Maybe they
should be functions instead?  They act like functions
in that a change function is called with the new
value.

For a couple of my functions (e.g., edit.m) I tried
to set up the equivalent of built-in variables for the
arbitrary defaults by using global variables.  This
mostly works except that it is slightly inconvenient
(you need to say global when initializing them from
octaverc) and it pollutes the global space.  Also,
when I save a value to a file, all global variables are
also saved in the file [is there a way to control this?].

Another approach would be property lists associated
with symbols, so I could set the 'author' property on the
edit symbol and edit could query that property.  This
won't work because edit isn't defined until it is called
the first time, but I want to set the properties from octaverc.

A third approach is to do the matlab like thing and
call the function with property pairs and save the property
values in persistent variables.  This I can do now, but
it is kind of ugly.

Suggestions