(Making this more general would also allow things like excluding two-slot howitzers from an autoloader, or making something that specifically improves heavy weapons)

Bumping as per request on stream: this is required for my implementation of the Sotho-class as a playership in Elemental Shift.

 Minor addendum: Being able to check for any property with something other than a true|nil value — +property:deviceSlots:1 or even something like +property:speed:100 or the like — would be nice, too (although at that point, you probably need to start being able to check for numeric ranges).

For flexibility, maybe criteria strings could specify a lambda function that will be called on the items/objects/types being checked (after they pass the other checks for performance reasons). This would allow for Boolean logic and checking non-Boolean properties like this one.

E.g.:

<DeviceSlot criteria="w +lambda:myFunction;"/>

<Globals>
	(setq myFunction (lambda (theItem)
		(leq (itmGetProperty theItem 'deviceSlots) 1)
		))
</Globals>

@AP and @NMS: I'm torn: On the one hand adding lambdas to criteria could unblock a lot of use-cases. On the other hand, something like AP's suggestion would execute faster and would be more intuitive for simple cases (like this request).

For example, I imagine something like:

criteria="w +property:deviceSlots=1"
criteria="w +property:deviceSlots>1"
criteria="w +property:deviceSlots<=2"
etc

[Of course, the fact that this is embedded in XML means we'd have to escape the greater/less-than operators.]

In contrast, using lambdas—even if embedded—would be more verbose:

criteria="w +lambda:(lambda (theItem) (gr (itmGetProperty theItem 'deviceSlots) 1));"

I'll probably try implementing the first and later allow lambdas.

In 1.8 Beta 4 I added the syntax described above. NOTE: Do not add spaces around the operators and make sure you use > and < as appropriate.