[Freeciv-Dev] (PR#12997) UnitFlag requirement

["Vasco Alexandre da Silva Costa" <vasc@xxxxxxxxxxxxxx>]

<URL: http://bugs.freeciv.org/Ticket/Display.html?id=12997 >

Since Jason's UnitType requirement is in CVS HEAD, we have unit effects.

So this leaves the whole LAND/SEA/AIR/MISSILE/_DEFEND nonsense to fix.

IMO we should use unit flags for implementing this. Using our
unit_class_id is a bad idea because classes are too inflexible compared
to flags.

Imagine we are implementing a MoM ruleset. Some units have increased
attack or defense vs certain types of units. Some units are Illusion,
others Death, others Chaos. Some may be Summoned or may have First
Strike. These traits are not necessarily exclusive. Flags allows you to
have non-mutually exclusive unit traits while classes make it nearly
impossible to do this.

I will try to make a demo patch soon.