From b9c78c92b254ddbb0cda49abd6e2378eff4af3ec Mon Sep 17 00:00:00 2001
From: upsilon <upsilon@langg.net>
Date: Sun, 16 Feb 2020 18:20:37 +0100
Subject: [PATCH] Make the data table different for each arrow I found myself
 discovering, while re-reading this code (and judging it not so readable,
 despite myself being its author), that data table of each arrow was in fact a
 single reference shared between all entities corresponding to an arrow of the
 same type. I'm really sorry about this and the catastrophes it may have
 caused (e.g., it made it easy to duplicate an item using a drop arrow by
 throwing a random item, and then throwing the item to duplicate before the
 first arrow hit the ground: both arrows would then produce the stack that was
 thrown last). I hope no player discovered this on a server that used this
 mod.

(Also, I don't really see the point of the make_arrow_def function anymore, so I removed it. I wrote this too long ago to remember why I would write such code.)
---
 init.lua | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/init.lua b/init.lua
index 7a27fb9..ed82789 100644
--- a/init.lua
+++ b/init.lua
@@ -43,10 +43,14 @@ local function shoot_arrow(itemstack, player, index, throw_itself, new_stack)
 	local obj = (minetest.registered_items[itemstack:get_name()].spawn_arrow_entity or throwing.spawn_arrow_entity)(pos, arrow, player)
 
 	local luaentity = obj:get_luaentity()
+
+	-- Set custom data in the entity
 	luaentity.player = player:get_player_name()
 	if not luaentity.item then
 		luaentity.item = arrow
 	end
+	luaentity.data = {}
+	luaentity.timer = 0
 
 	if luaentity.on_throw then
 		if luaentity:on_throw(pos, player, arrow_stack, index, luaentity.data) == false then
@@ -203,14 +207,6 @@ local function arrow_step(self, dtime)
 	self.last_pos = pos -- Used by the build arrow
 end
 
-function throwing.make_arrow_def(def)
-	def.timer = 0
-	def.player = ""
-	def.on_step = arrow_step
-	def.data = {}
-	return def
-end
-
 --[[
 on_hit(pos, last_pos, node, object, hitter)
 Either node or object is nil, depending whether the arrow collided with an object (luaentity or player) or with a node.
@@ -276,7 +272,7 @@ function throwing.register_arrow(name, def)
 	}
 	minetest.register_node(registration_name, def)
 
-	minetest.register_entity(registration_name.."_entity", throwing.make_arrow_def{
+	minetest.register_entity(registration_name.."_entity", {
 		physical = false,
 		visual = "wielditem",
 		visual_size = {x = 0.125, y = 0.125},
@@ -289,6 +285,7 @@ function throwing.register_arrow(name, def)
 		allow_protected = def.allow_protected,
 		target = def.target,
 		on_hit_fails = def.on_hit_fails,
+		on_step = arrow_step,
 		item = name,
 	})
 end