Lua API: Add function to deregister single biomes (#5445)

builtin/game/register.lua

@@ -505,6 +505,19 @@ local function make_registration_wrap(reg_fn_name, clear_fn_name)
 	return list
 end
 
+local function make_wrap_deregistration(reg_fn, clear_fn, list)
+	local unregister = function (unregistered_key)
+		local temporary_list = table.copy(list)
+		clear_fn()
+		for k,v in pairs(temporary_list) do
+			if unregistered_key ~= k then
+				reg_fn(v)
+			end
+		end
+	end
+	return unregister
+end
+
 core.registered_on_player_hpchanges = { modifiers = { }, loggers = { } }
 
 function core.registered_on_player_hpchange(player, hp_change)
@@ -543,6 +556,8 @@ core.registered_biomes      = make_registration_wrap("register_biome",      "cle
 core.registered_ores        = make_registration_wrap("register_ore",        "clear_registered_ores")
 core.registered_decorations = make_registration_wrap("register_decoration", "clear_registered_decorations")
 
+core.unregister_biome = make_wrap_deregistration(core.register_biome, core.clear_registered_biomes, core.registered_biomes)
+
 core.registered_on_chat_messages, core.register_on_chat_message = make_registration()
 core.registered_globalsteps, core.register_globalstep = make_registration()
 core.registered_playerevents, core.register_playerevent = make_registration()

doc/lua_api.txt

@@ -715,6 +715,10 @@ the global `minetest.registered_*` tables.
     * added to `minetest.registered_biome` with the key of `biome.name`
     * if `biome.name` is nil, the key is the returned ID
 
+* `minetest.unregister_biome(name)`
+    * Unregisters the biome name from engine, and deletes the entry with key
+    * `name` from `minetest.registered_biome`
+
 * `minetest.register_ore(ore definition)`
     * returns an integer uniquely identifying the registered ore
     * added to `minetest.registered_ores` with the key of `ore.name`