Accept [effect] in [modify_unit]

changelog

@@ -15,6 +15,9 @@ Version 1.13.5+dev:
      - [else] sub-tag, WML to execute if no unit found for the role
    * New help_text= key for [trait] to set the description displayed in the help.
    * Added tag id= [fire_event], which allows raising events by id
+   * [modify_unit] now understands [effect] tags, which it applies directly.
+     This replaces the use of [object] with no_write=yes (which will be removed
+     in the next release).
  * Lua API:
    * Added new functions wesnoth.fire_event_by_id and fire_event_by_name. The old
      function wesnoth.fire_event is now an alias for wesnoth.fire_event_by_name

data/lua/wml/modify_unit.lua

@@ -51,6 +51,18 @@ function wml_actions.modify_unit(cfg)
 				wesnoth.add_modification(unit, current_tag, mod)
 				unit = unit.__cfg;
 				wesnoth.set_variable(unit_path, unit)
+			elseif current_tag == "effect" then
+				local mod = current_table[2]
+				local apply_to = mod.apply_to
+				if wesnoth.effects[apply_to] then
+					local unit = wesnoth.get_variable(unit_path)
+					unit = wesnoth.create_unit(unit)
+					wesnoth.effects[apply_to](unit, mod)
+					unit = unit.__cfg;
+					wesnoth.set_variable(unit_path, unit)
+				else
+					helper.wml_error("[modify_unit] had invalid [effect]apply_to value")
+				end
 			else
 				local tag_index = children_handled[current_tag] or 0
 				handle_child(current_table[2], string.format("%s.%s[%u]",

data/lua/wml/object.lua

@@ -27,6 +27,10 @@ function wml_actions.object(cfg)
 		text = tostring(cfg.description or "")
 		command_type = "then"
 
+		if cfg.no_write ~= nil then
+			wesnoth.log("wml", "[object]no_write=yes is deprecated in favour of placing [effect] tags in [modify_unit]")
+		end
+
 		local dvs = cfg.delayed_variable_substitution
 		local add = cfg.no_write ~= true
 		if dvs then

src/scripting/game_lua_kernel.cpp

@@ -3613,6 +3613,9 @@ static int intf_add_modification(lua_State *L)
 	if (!lua_isnone(L, 4)) {
 		write_to_mods = luaW_toboolean(L, 4);
 	}
+	if(sm.empty()) {
+		write_to_mods = false;
+	}
 
 	config cfg = luaW_checkconfig(L, 3);
 	u.add_modification(sm, cfg, !write_to_mods);