nalc-server/custom/mods/nalc/nalc_lib/init.lua

nalc = {}

-- Remove node from a group
local function remove_group(name, group)
	local node = minetest.registered_nodes[name]
	
	if node then
		local groups = node.groups
		if groups then
			for g in pairs(groups) do
				if g == group then
					groups[g] = 0
					minetest.log("action", "[nalc_lib] "..name.." removed from group "..group..".")
				end
			end
			minetest.override_item(name, {groups = groups})
		else
			minetest.log("warning", "[nalc_lib] "..name.." has no groups, could not remove group "..group..".")
		end
	else
		minetest.log("warning", "[nalc_lib] "..name.." not registered, could not remove group "..group..".")
	end
end

-- Add node to group
local function add_group(name, group, value)
	local node = minetest.registered_nodes[name]

	if node then
		local groups = node.groups
		if not groups then
			groups = {}
		end
		groups[group] = value

		minetest.log("action", "[nalc_lib] Add group "..group.."="..value.." to "..name)
		minetest.override_item(name, {groups = groups})
	end
end

-- Add a node in xp group
function nalc.def_xp(name, value)
	add_group(name, "xp", value)
end

-- Remove node from group "oddly_breakable_by_hand"
function nalc.not_hand_breakable(name)
	remove_group(name, "oddly_breakable_by_hand")
end