Then no return value (same as CyPlayer.chooseTech()).
You're right, but I can add it as new promotion properties (And see below for my take on the subject).
Actually, the way I see it, this is exactly what seasnake wants: Give some kind of a promotion to all units of a specific player.
The fact that there are no existing promotions that enable this does not change this fact. And as a player it will be easier for me to see it as a promotion for a unit.
How else will you represent it in the UI?
But this is of course up to seasnake: if you want me to do this directly and not using a promotion - it's your call.
Now for specifics:
What exactly does domestic/foreign combat bonus cover? Is foreign = enemy? is it enemy+neutral? (same question for healing)
I assume that this bonus acts like (for example) combat I: + X% combat for both attack and defense?
What happens in the case where an enemy unit standing in a foreign territory plot, my unit is standing in my territory, and this enemy unit attacks my unit? And what happens vice versa?
And about the healing - units can already heal in enemy territory, but it's slower than in friendly or neutral territory. So what does 'UnitsCanHealInForeignTerritory' mean exactly?
Actually, I would want it to show up in the UI like when you show the combat odds, somethinig "+10 percent bonus in enemy territory" similar to something like "+25 percent against Barbarian units" and be a direct power, not a promotion. Of course I am more than willing to do it via a promotion, but if I'm picking and dreaming it's handled like that.
Foreign means "battle occurs in territory owned by my enemy." I'm wishing for a system where you attack and the game determines who is the owner of the plot where the combat is occurring and whether or not France is at war with this player, and if yes France gets the bonus. The deciding factor on the bonus is where the combat occurs, so if I am in my territory and my enemy is in his territory and our borders touch, I am better served to cross the border and attack him. Likewise, domestic bonus means that if I am in my territory I'm better off staying there if possible.
If this is possible that's what I want. If it's not, or someone has a better idea, I'm I'm totally okay going about it a different way to get the desired result. But as it stands I'd like to avoid using a promotion unless there's a good reason to do so.
Oh, and for each civ I'm writing a strategy guide of sorts for their CivPedia page that will explain their bonuses and offer advice, so exactly how the bonus works for the French and the Iroquois will be explained thoroughly.
As for healing and unit upgrading, change that to read "outside own borders." So the French combat bonus occurs in Enemy territory, not neutral, and the healing/upgrade bonus occurs in neutral and enemy territory.
Hope that clears that up some.