> Brendan wonders if vgui can be in the core if it depends on other core
> libraries, i.e., vil. In my view such dependencies are ok.
That is indeed what we agreed upon when vxl was designed.
The exact conventions are as follows:
- level-1 libraries cannot depend on each other
(but can depend on vcl, of course)
- level-2 libraries cannot depend on each other,
but can depend on any level-1 libraries.
Thus, if vgui becomes a level-2 library (which it actually already
is) if may depend on vnl, vil, vgl, vbl, vul, vsl, but not on e.g.
vidl or vsol. It can be disputed whether it may depend on vnl-io,
vnl-algo, vgl-algo etc. since those are certainly not level-1 libs
(at most somewhere inbetween level-1 and level-2).
> Maybe the answer is alternative tableaux, e.g., vgui_vgl_tableau,
> a sub-class of vgui_easy2D_tableau?
Good idea! Actually, I see "vgui" more or less like "vsl", the file
based I/O library: vgui is a kind of graphical I/O for the rest of
vxl. In that respect, I can live with the idea of a level-1 vgui
core library (more or less independent of all level-1 libs except of
course from vil; so pure a level-1 vgui is probably impossible), and
additionally a set of interface libraries for each level-1 or level-2
library that requires it, just like the vnl-io etc libs.