Remove soft dependency on 'technic'

This avoids dependency chains as reported in issue N° 125.

Author: SmallJoker

mod.conf

@@ -3,7 +3,8 @@ title = Digtron
 author = FaceDeer
 description = Adds components for building modular tunnel boring machines.
 depends = default, fakelib
-optional_depends = pipeworks, doc, hopper, awards, catacomb, intllib, technic
+optional_depends = pipeworks, doc, hopper, awards, catacomb, intllib
+# ^ Note: 'technic' is omitted to break dependency chains.
 license = MIT, LGPL 2.1 or later
 forum = https://forum.luanti.org/viewtopic.php?t=16295
 version = 0.8

nodes/node_battery_holder.lua

@@ -2,7 +2,7 @@
 local S = digtron.S
 -- local MP = minetest.get_modpath(minetest.get_current_modname())
 -- local S = dofile(MP.."/intllib.lua")
-
+local have_technic_mod = core.get_modpath("technic")
 
 -- Battery storage. Controller node draws electrical power from here.
 -- Note that batttery boxes are digtron group 7.
@@ -24,7 +24,7 @@ local battery_holder_formspec = function()
 end
 
 local holder_groups = {cracky = 3,  oddly_breakable_by_hand = 3, digtron = 7, tubedevice = 1, tubedevice_receiver = 1}
-if not minetest.get_modpath("technic") then
+if not have_technic_mod then
 	-- if technic isn't installed there's no point in offering battery holders.
 	-- leave them registered, though, in case technic is being removed from an existing server.
 	holder_groups.not_in_creative_inventory = 1
@@ -66,8 +66,12 @@ local def = {
 
 	-- Allow all items with energy storage to be placed in the inventory
 	allow_metadata_inventory_put = function(pos, listname, _, stack, player)
+		if not have_technic_mod then
+			return 0
+		end
+
 		if listname == "batteries" then
-			if minetest.global_exists("technic") and technic.get_charge(stack) > 0 then
+			if technic.get_charge(stack) > 0 then
 				if digtron.check_protected_and_record(pos, player) then
 					return 0
 				end
@@ -99,8 +103,12 @@ local def = {
 			return inv:add_item("batteries", stack)
 		end,
 		can_insert = function(pos, _, stack)
+			if not have_technic_mod then
+				return false
+			end
+
 			-- Disregard empty batteries, the player should know better
-			if minetest.global_exists("technic") and technic.get_charge(stack) > 0 then
+			if technic.get_charge(stack) > 0 then
 				local meta = minetest.get_meta(pos)
 				local inv = meta:get_inventory()
 				return inv:room_for_item("batteries", stack)

nodes/node_power_connector.lua

@@ -2,6 +2,7 @@
 local S = digtron.S
 -- local MP = minetest.get_modpath(minetest.get_current_modname())
 -- local S = dofile(MP.."/intllib.lua")
+local have_technic_mod = core.get_modpath("technic")
 
 local size = 3/16
 
@@ -19,7 +20,7 @@ local get_formspec_string = function(current_val, current_max)
 end
 
 local connector_groups = {cracky = 3, oddly_breakable_by_hand=3, digtron = 8, technic_machine=1, technic_hv=1}
-if not minetest.get_modpath("technic") then
+if not have_technic_mod then
 	-- Technic is not installed, hide this away.
 	connector_groups.not_in_creative_inventory = 1
 end
@@ -100,6 +101,10 @@ minetest.register_node("digtron:power_connector", {
 	end,
 })
 
-if minetest.get_modpath("technic") then
-	technic.register_machine("HV", "digtron:power_connector", technic.receiver)
-end
+-- To avoid dependency chains, delay the machine registration. But allow post-processing
+-- by other mods by running this callback at the first chance.
+table.insert(core.registered_on_mods_loaded, 1, function()
+	if have_technic_mod then
+		technic.register_machine("HV", "digtron:power_connector", technic.receiver)
+	end
+end)

nodes/recipes.lua

@@ -2,6 +2,7 @@
 local S = digtron.S
 -- local MP = minetest.get_modpath(minetest.get_current_modname())
 -- local S = dofile(MP.."/intllib.lua")
+local have_technic_mod = core.get_modpath("technic")
 
 minetest.register_craftitem("digtron:digtron_core", {
 	description = S("Digtron Core"),
@@ -46,7 +47,7 @@ minetest.register_craft({
 			}
 })
 
-if minetest.get_modpath("technic") then
+if have_technic_mod then
 	minetest.register_craft({
 		output = "digtron:master_builder",
 		recipe = {
@@ -111,7 +112,7 @@ minetest.register_craft({
 			}
 })
 
-if minetest.get_modpath("technic") then
+if have_technic_mod then
 	-- no need for this recipe if technic is not installed, avoid cluttering crafting guides
 	minetest.register_craft({
 		output = "digtron:battery_holder",

util.lua

@@ -5,6 +5,8 @@ dofile( minetest.get_modpath( "digtron" ) .. "/util_execute_cycle.lua" ) -- sepa
 
 local node_inventory_table = {type="node"} -- a reusable parameter for get_inventory calls, set the pos parameter before using.
 
+local have_technic_mod = core.get_modpath("technic")
+
 -- Apparently node_sound_metal_defaults is a newer thing, I ran into games using an older version of the default mod without it.
 if default.node_sound_metal_defaults ~= nil then
 	digtron.metal_sounds = default.node_sound_metal_defaults()
@@ -279,7 +281,7 @@ digtron.tap_batteries = function(battery_positions, target, test)
 		end
 
 		for _, itemstack in pairs(invlist) do
-			if minetest.global_exists("technic") then
+			if have_technic_mod then
 				local power_available = math.floor(technic.get_charge(itemstack) / digtron.config.power_ratio)
 				if power_available ~= 0 then
 					local actual_burned = power_available -- we just take all we have from the battery, since they aren't stackable