SDB note about philosophy behind globals
I made the "TOPLEVEL project" and all the GTK window stuff into global variables. I know that this is supposedly bad programming form. However, here are some observations:
- I wanted to use gEDA's TOPLEVEL structure as much as possible, at least to hold info about the design's netlist & components. The TOPLEVEL strucuture is architected to hold info about gschem's window also. HOwever, gschem's windows are architected differently than mine in gattrib. This is because my windowing system does completely different things, and also uses the GtkSheet widget, which is architected completely differently from TOPLEVEL.
- Since I couldn't easily or naturally cram my windowing scheme into TOPLEVEL (or so I think), I decided to use a separate set of windows from those defined under TOPLEVEL for my application.
- The problem arises when using callbacks. Callbacks from GTK allow only one argument to be passed. Given the way I set up the menu bar, I didn't have easy acces to the information inside both the GtkSHeet objects *and* the TOPLEVEL stuff while only having one callback argument. This makes it hard to have access to e.g. a GtkSheet window and a list of files (in TOPLEVEL) simultaneously.
- Therefore, I decided to make both the window stuff and TOPLEVEL globals.
- Similarly, because I couldn't cram the SHEET_DATA struct into any hook in TOPLEVEL, I just made it a global also.
- Finally, in my defense, in gschem and gnetlist, (TOPLEVEL *w_current or pr_current) is passed to almost every function. Since it is just a pointer to a huge struct of stuff, manipulating the stuff in the struct has a global effect. That is, manipulating w_current (or pr_current) has side effects, so it is basically a global anyway. The real problem with globals occurs when you have a global variable caled "i" or "temp" which conflicts with a global in a module written by somebody else. Since pr_current is a very uncommon name, this should not be a problem here. Therefore, I decided to make life easy for myself dealing with callbacks by making both the windows and TOPLEVEL global variables.
If there is a better way to solve this problem, I'd like to hear it.
Definition in file globals.h.
1.7.3 
