Add __tostring metamethods to textdomains, races, unit types, weapons, and sides

changelog.md

@@ -54,6 +54,7 @@
    * Moved to new sides module: wesnoth.get_sides, wesnoth.is_enemy, wesnoth.match_side, wesnoth.get_starting_location, wesnoth.set_side_id, all AI-related functions
    * Functions that previously only took a side index as the first parameter now also accept the side proxy userdata.
    * The wesnoth.sides module acts like a metatable for the side userdata.
+   * Added `__tostring` functions to a number of Wesnoth userdata types.
  ### WML engine
    * Support upkeep in StandardUnitFilter
    * [effect]apply_to=variation now supports heal_full

src/scripting/lua_common.cpp

@@ -24,6 +24,7 @@
 #include "scripting/lua_common.hpp"
 
 #include "config.hpp"
+#include "scripting/push_check.hpp"
 #include "scripting/lua_unit.hpp"
 #include "tstring.hpp"                  // for t_string
 #include "variable.hpp" // for vconfig
@@ -75,6 +76,15 @@ static int impl_gettext(lua_State *L)
 	return 1;
 }
 
+static int impl_gettext_tostr(lua_State* L)
+{
+	char* d = static_cast<char*>(lua_touserdata(L, 1));
+	using namespace std::literals;
+	std::string str = "textdomain: "s + d;
+	lua_push(L, str);
+	return 1;
+}
+
 /**
  * Creates an interface for gettext
  * - Arg 1: string containing the domain.
@@ -403,6 +413,7 @@ std::string register_gettext_metatable(lua_State *L)
 
 	static luaL_Reg const callbacks[] {
 		{ "__call", 	    &impl_gettext},
+		{ "__tostring",     &impl_gettext_tostr},
 		{ nullptr, nullptr }
 	};
 	luaL_setfuncs(L, callbacks, 0);

src/scripting/lua_race.cpp

@@ -16,6 +16,7 @@
 
 #include "units/race.hpp"
 #include "scripting/lua_common.hpp"
+#include "scripting/push_check.hpp"
 #include "units/types.hpp"
 
 #include <string>
@@ -41,12 +42,8 @@ static const char * Gen = "name generator";
  */
 static int impl_race_get(lua_State* L)
 {
+	const unit_race& race = luaW_checkrace(L, 1);
 	char const* m = luaL_checkstring(L, 2);
-	lua_pushstring(L, "id");
-	lua_rawget(L, 1);
-	const unit_race* raceptr = unit_types.find_race(lua_tostring(L, -1));
-	if(!raceptr) return luaL_argerror(L, 1, "unknown race");
-	const unit_race& race = *raceptr;
 
 	return_tstring_attrib("description", race.description());
 	return_tstring_attrib("name", race.name());
@@ -89,6 +86,18 @@ static int impl_race_get(lua_State* L)
 	return 0;
 }
 
+/**
+ * Turns a lua proxy race to string. (__tostring metamethod)
+ */
+static int impl_race_tostring(lua_State* L)
+{
+	const unit_race& race = luaW_checkrace(L, 1);
+	std::ostringstream str;
+	str << "race: <" << race.id() << '>';
+	lua_push(L, str.str());
+	return 1;
+}
+
 namespace lua_race {
 
 	std::string register_metatable(lua_State * L)
@@ -97,6 +106,7 @@ namespace lua_race {
 
 		static luaL_Reg const callbacks[] {
 			{ "__index", 	    &impl_race_get},
+			{ "__tostring",     &impl_race_tostring},
 			{ nullptr, nullptr }
 		};
 		luaL_setfuncs(L, callbacks, 0);
@@ -128,3 +138,15 @@ void luaW_pushracetable(lua_State *L)
 		lua_setfield(L, -2, race.first.c_str());
 	}
 }
+
+const unit_race& luaW_checkrace(lua_State* L, int idx)
+{
+	lua_pushstring(L, "id");
+	lua_rawget(L, idx);
+	const unit_race* raceptr = unit_types.find_race(lua_tostring(L, -1));
+	if(!raceptr) {
+		luaL_argerror(L, idx, "unknown race");
+		throw "UNREACHABLE";
+	}
+	return *raceptr;
+}

src/scripting/lua_race.hpp

@@ -30,3 +30,4 @@ namespace lua_race {
 // Create a lua reference to the race.
 void luaW_pushrace(lua_State *, const unit_race &);
 void luaW_pushracetable(lua_State *);
+const unit_race& luaW_checkrace(lua_State*, int);

src/scripting/lua_team.cpp

@@ -15,6 +15,7 @@
 #include "scripting/lua_team.hpp"
 
 #include "scripting/lua_common.hpp"
+#include "scripting/push_check.hpp"
 #include "scripting/game_lua_kernel.hpp"
 #include "team.hpp"
 #include "resources.hpp" // for gameboard
@@ -126,6 +127,24 @@ static int impl_side_get(lua_State *L)
 	return 0;
 }
 
+/**
+ * Turns a lua proxy side to string. (__tostring metamethod)
+ */
+static int impl_side_tostring(lua_State* L)
+{
+	const team& team = luaW_checkteam(L, 1);
+	std::ostringstream str;
+
+	str << "side: <" << team.side();
+	if(!team.side_name().empty()) {
+		str << " " << team.side_name();
+	}
+	str << '>';
+
+	lua_push(L, str.str());
+	return 1;
+}
+
 /**
  * Sets some data on a side (__newindex metamethod).
  * - Arg 1: full userdata containing the team.
@@ -287,6 +306,7 @@ namespace lua_team {
 			{ "__index", 	    &impl_side_get},
 			{ "__newindex",	    &impl_side_set},
 			{ "__eq",	        &impl_side_equal},
+			{ "__tostring",     &impl_side_tostring},
 			{ nullptr, nullptr }
 		};
 		luaL_setfuncs(L, callbacks, 0);

src/scripting/lua_unit_attacks.cpp

@@ -17,6 +17,7 @@
 #include "scripting/lua_common.hpp"
 #include "scripting/lua_unit.hpp"
 #include "scripting/lua_unit_type.hpp"
+#include "scripting/push_check.hpp"
 #include "units/unit.hpp"
 #include "units/attack_type.hpp"
 #include "utils/const_clone.hpp"
@@ -314,6 +315,18 @@ static int impl_unit_attack_equal(lua_State* L)
 	return 1;
 }
 
+/**
+ * Turns a lua proxy attack to string. (__tostring metamethod)
+ */
+static int impl_unit_attack_tostring(lua_State* L)
+{
+	const_attack_ptr atk = luaW_checkweapon_ref(L, 1).cattack;
+	std::ostringstream str;
+	str << "weapon: <" << atk->id() << '>';
+	lua_push(L, str.str());
+	return 1;
+}
+
 static int impl_unit_attack_match(lua_State* L)
 {
 	const_attack_ptr atk = luaW_toweapon(L, 1);
@@ -367,6 +380,8 @@ namespace lua_units {
 		lua_setfield(L, -2, "__newindex");
 		lua_pushcfunction(L, impl_unit_attack_equal);
 		lua_setfield(L, -2, "__eq");
+		lua_pushcfunction(L, impl_unit_attack_tostring);
+		lua_setfield(L, -2, "__tostring");
 		lua_pushcfunction(L, impl_unit_attack_collect);
 		lua_setfield(L, -2, "__gc");
 		lua_pushstring(L, uattackKey);

src/scripting/lua_unit_type.cpp

@@ -186,6 +186,20 @@ static int impl_unit_type_pairs(lua_State* L) {
 	return 3;
 }
 
+/**
+ * Turns a lua proxy unit type to string. (__tostring metamethod)
+ */
+static int impl_unit_type_tostring(lua_State* L)
+{
+	const unit_type& ut = luaW_checkunittype(L, 1);
+	std::ostringstream str;
+
+	str << "unit type: <" << ut.id() << '>';
+
+	lua_push(L, str.str());
+	return 1;
+}
+
 namespace lua_unit_type {
 	std::string register_metatable(lua_State * L)
 	{
@@ -193,6 +207,8 @@ namespace lua_unit_type {
 
 		lua_pushcfunction(L, impl_unit_type_get);
 		lua_setfield(L, -2, "__index");
+		lua_pushcfunction(L, impl_unit_type_tostring);
+		lua_setfield(L, -2, "__tostring");
 		lua_pushcfunction(L, impl_unit_type_equal);
 		lua_setfield(L, -2, "__eq");
 		lua_pushstring(L, UnitType);