Change naming convention to be modname:* instead of modname_* (sorry modders!)

data/mods/bucket/init.lua

@@ -1,12 +1,12 @@
 minetest.register_craft({
-	output = 'craft "bucket_empty" 1',
+	output = 'craft "bucket:bucket_empty" 1',
 	recipe = {
 		{'craft "steel_ingot"', '', 'craft "steel_ingot"'},
 		{'', 'craft "steel_ingot"', ''},
 	}
 })
 
-minetest.register_craftitem("bucket_empty", {
+minetest.register_craftitem("bucket:bucket_empty", {
 	image = "bucket.png",
 	stack_max = 1,
 	liquids_pointable = true,
@@ -16,11 +16,11 @@ minetest.register_craftitem("bucket_empty", {
 			n = minetest.env:get_node(pointed_thing.under)
 			if n.name == "water_source" then
 				minetest.env:add_node(pointed_thing.under, {name="air"})
-				player:add_to_inventory_later('craft "bucket_water" 1')
+				player:add_to_inventory_later('craft "bucket:bucket_water" 1')
 				return true
 			elseif n.name == "lava_source" then
 				minetest.env:add_node(pointed_thing.under, {name="air"})
-				player:add_to_inventory_later('craft "bucket_lava" 1')
+				player:add_to_inventory_later('craft "bucket:bucket_lava" 1')
 				return true
 			end
 		end
@@ -28,8 +28,8 @@ minetest.register_craftitem("bucket_empty", {
 	end,
 })
 
-minetest.register_craftitem("bucket_water", {
-	image = "bucket_water.png",
+minetest.register_craftitem("bucket:bucket_water", {
+	image = "bucket:bucket_water.png",
 	stack_max = 1,
 	liquids_pointable = true,
 	on_place_on_ground = minetest.craftitem_place_item,
@@ -43,15 +43,15 @@ minetest.register_craftitem("bucket_water", {
 			else
 				minetest.env:add_node(pointed_thing.above, {name="water_source"})
 			end
-			player:add_to_inventory_later('craft "bucket_empty" 1')
+			player:add_to_inventory_later('craft "bucket:bucket_empty" 1')
 			return true
 		end
 		return false
 	end,
 })
 
-minetest.register_craftitem("bucket_lava", {
-	image = "bucket_lava.png",
+minetest.register_craftitem("bucket:bucket_lava", {
+	image = "bucket:bucket_lava.png",
 	stack_max = 1,
 	liquids_pointable = true,
 	on_place_on_ground = minetest.craftitem_place_item,
@@ -65,7 +65,7 @@ minetest.register_craftitem("bucket_lava", {
 			else
 				minetest.env:add_node(pointed_thing.above, {name="lava_source"})
 			end
-			player:add_to_inventory_later('craft "bucket_empty" 1')
+			player:add_to_inventory_later('craft "bucket:bucket_empty" 1')
 			return true
 		end
 		return false

data/mods/default/init.lua

@@ -21,17 +21,21 @@
 --
 -- Naming convention for registered textual names
 -- ----------------------------------------------
--- "modname_<whatever>"
+-- "modname:<whatever>" (<whatever> can have characters a-zA-Z0-9_)
 --
 -- This is to prevent conflicting names from corrupting maps and is
 -- enforced by the mod loader.
 --
 -- Example: mod "experimental", ideal item/node/entity name "tnt":
---          -> the name should be "experimental_tnt".
+--          -> the name should be "experimental:tnt".
 --
 -- Enforcement can be overridden by prefixing the name with ":". This can
 -- be used for overriding the registrations of some other mod.
 --
+-- Example: Any mod can redefine experimental:tnt by using the name
+--          ":experimental:tnt" when registering it.
+-- (also that mods is required to have "experimental" as a dependency)
+--
 -- Default mod uses ":" for maintaining backwards compatibility.
 --
 -- Textures
@@ -1426,7 +1430,7 @@ function nodeupdate_single(p)
 		n_bottom = minetest.env:get_node(p_bottom)
 		if n_bottom.name == "air" then
 			minetest.env:remove_node(p)
-			minetest.env:add_luaentity(p, "default_falling_"..n.name)
+			minetest.env:add_luaentity(p, "default:falling_"..n.name)
 			nodeupdate(p)
 		end
 	end
@@ -1448,7 +1452,7 @@ end
 --
 
 function register_falling_node(nodename, texture)
-	minetest.register_entity("default_falling_"..nodename, {
+	minetest.register_entity("default:falling_"..nodename, {
 		-- Static definition
 		physical = true,
 		collisionbox = {-0.5,-0.5,-0.5, 0.5,0.5,0.5},

data/mods/experimental/init.lua

@@ -4,7 +4,7 @@
 
 -- An example furnace-thing implemented in Lua
 
-minetest.register_node("experimental_luafurnace", {
+minetest.register_node("experimental:luafurnace", {
 	tile_images = {"lava.png", "furnace_side.png", "furnace_side.png",
 		"furnace_side.png", "furnace_side.png", "furnace_front.png"},
 	--inventory_image = "furnace_front.png",
@@ -15,7 +15,7 @@ minetest.register_node("experimental_luafurnace", {
 })
 
 minetest.register_on_placenode(function(pos, newnode, placer)
-	if newnode.name == "experimental_luafurnace" then
+	if newnode.name == "experimental:luafurnace" then
 		print("get_meta");
 		local meta = minetest.env:get_meta(pos)
 		print("inventory_set_list");
@@ -42,7 +42,7 @@ minetest.register_on_placenode(function(pos, newnode, placer)
 end)
 
 minetest.register_abm({
-	nodenames = {"experimental_luafurnace"},
+	nodenames = {"experimental:luafurnace"},
 	interval = 1.0,
 	chance = 1,
 	action = function(pos, node, active_object_count, active_object_count_wider)
@@ -97,7 +97,7 @@ minetest.register_abm({
 })
 
 minetest.register_craft({
-	output = 'node "experimental_luafurnace" 1',
+	output = 'node "experimental:luafurnace" 1',
 	recipe = {
 		{'node "cobble"', 'node "cobble"', 'node "cobble"'},
 		{'node "cobble"', 'node "cobble"', 'node "cobble"'},
@@ -132,7 +132,7 @@ minetest.register_craft({
 	}
 })
 
-minetest.register_node("experimental_somenode", {
+minetest.register_node("experimental:somenode", {
 	tile_images = {"lava.png", "mese.png", "stone.png", "grass.png", "cobble.png", "tree_top.png"},
 	inventory_image = "treeprop.png",
 	material = {
@@ -151,7 +151,7 @@ minetest.register_node("experimental_somenode", {
 --
 
 minetest.register_craft({
-	output = 'node "experimental_tnt" 4',
+	output = 'node "experimental:tnt" 4',
 	recipe = {
 		{'node "wood" 1'},
 		{'craft "lump_of_coal" 1'},
@@ -159,7 +159,7 @@ minetest.register_craft({
 	}
 })
 
-minetest.register_node("experimental_tnt", {
+minetest.register_node("experimental:tnt", {
 	tile_images = {"tnt_top.png", "tnt_bottom.png", "tnt_side.png", "tnt_side.png", "tnt_side.png", "tnt_side.png"},
 	inventory_image = "tnt_side.png",
 	dug_item = '', -- Get nothing
@@ -169,9 +169,9 @@ minetest.register_node("experimental_tnt", {
 })
 
 minetest.register_on_punchnode(function(p, node)
-	if node.name == "experimental_tnt" then
+	if node.name == "experimental:tnt" then
 		minetest.env:remove_node(p)
-		minetest.env:add_luaentity(p, "experimental_tnt")
+		minetest.env:add_luaentity(p, "experimental:tnt")
 		nodeupdate(p)
 	end
 end)
@@ -235,13 +235,13 @@ end
 
 --print("TNT dump: "..dump(TNT))
 --print("Registering TNT");
-minetest.register_entity("experimental_tnt", TNT)
+minetest.register_entity("experimental:tnt", TNT)
 
 --
 -- A test entity for testing animated and yaw-modulated sprites
 --
 
-minetest.register_entity("experimental_testentity", {
+minetest.register_entity("experimental:testentity", {
 	-- Static definition
 	physical = true, -- Collides with things
 	-- weight = 5,

src/scriptapi.cpp

@@ -154,10 +154,17 @@ void check_modname_prefix(lua_State *L, std::string &name)
 	if(modname == "__builtin")
 		return;
 	
-	if(name.substr(0, modname.size()+1) != modname + "_")
+	if(name.substr(0, modname.size()+1) != modname + ":")
 		throw LuaError(L, std::string("Name \"")+name
 				+"\" does not follow naming conventions: "
-				+"\"modname_\" or \":\" prefix required)");
+				+"\"modname:\" or \":\" prefix required)");
+	
+	std::string subname = name.substr(modname.size()+1);
+	if(!string_allowed(subname, "abcdefghijklmnopqrstuvwxyz"
+			"ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_"))
+		throw LuaError(L, std::string("Name \"")+name
+				+"\" does not follow naming conventions: "
+				+"\"contains unallowed characters)");
 }
 
 static v3f readFloatPos(lua_State *L, int index)