Reworked ReturnByValue, warn_or_error, expect_date_[identifier_or_]string

17 files changed, 124 insertions, 96 deletions

diff --git a/src/openvic-simulation/dataloader/NodeTools.cpp b/src/openvic-simulation/dataloader/NodeTools.cpp
index 7ab0dbe..297937a 100644
--- a/src/openvic-simulation/dataloader/NodeTools.cpp
+++ b/src/openvic-simulation/dataloader/NodeTools.cpp
@@ -169,6 +169,14 @@ node_callback_t NodeTools::expect_date(callback_t<Date> callback) {
 	return expect_identifier(expect_date_str(callback));
 }
 
+node_callback_t NodeTools::expect_date_string(callback_t<Date> callback) {
+	return expect_string(expect_date_str(callback));
+}
+
+node_callback_t NodeTools::expect_date_identifier_or_string(callback_t<Date> callback) {
+	return expect_identifier_or_string(expect_date_str(callback));
+}
+
 node_callback_t NodeTools::expect_years(callback_t<Timespan> callback) {
 	return expect_uint<Timespan::day_t>([callback](Timespan::day_t val) -> bool {
 		return callback(Timespan::from_years(val));
diff --git a/src/openvic-simulation/dataloader/NodeTools.hpp b/src/openvic-simulation/dataloader/NodeTools.hpp
index 54b61d0..c41c09e 100644
--- a/src/openvic-simulation/dataloader/NodeTools.hpp
+++ b/src/openvic-simulation/dataloader/NodeTools.hpp
@@ -119,6 +119,8 @@ namespace OpenVic {
 
 		callback_t<std::string_view> expect_date_str(callback_t<Date> callback);
 		node_callback_t expect_date(callback_t<Date> callback);
+		node_callback_t expect_date_string(callback_t<Date> callback);
+		node_callback_t expect_date_identifier_or_string(callback_t<Date> callback);
 		node_callback_t expect_years(callback_t<Timespan> callback);
 		node_callback_t expect_months(callback_t<Timespan> callback);
 		node_callback_t expect_days(callback_t<Timespan> callback);
@@ -371,15 +373,15 @@ namespace OpenVic {
 
 		template<typename T, StringMapCase Case>
 		Callback<std::string_view> auto expect_mapped_string(
-			template_string_map_t<T, Case> const& map, Callback<T> auto callback
+			template_string_map_t<T, Case> const& map, Callback<T> auto callback, bool warn = false
 		) {
-			return [&map, callback](std::string_view string) -> bool {
+			return [&map, callback, warn](std::string_view string) -> bool {
 				const typename template_string_map_t<T, Case>::const_iterator it = map.find(string);
 				if (it != map.end()) {
 					return callback(it->second);
 				}
-				Logger::error("String not found in map: ", string);
-				return false;
+				Logger::warn_or_error(warn, "String not found in map: ", string);
+				return warn;
 			};
 		}
 
@@ -470,24 +472,14 @@ namespace OpenVic {
 			};
 		}
 
-		template<typename... Args>
-		bool warn_or_error(bool warn, Args&&... args) {
-			if (warn) {
-				Logger::warning(std::forward<Args>(args)...);
-				return true;
-			} else {
-				Logger::error(std::forward<Args>(args)...);
-				return false;
-			}
-		}
-
 		template<typename T, typename U, typename... SetArgs>
 		Callback<T> auto set_callback(tsl::ordered_set<U, SetArgs...>& set, bool warn = false) {
 			return [&set, warn](T val) -> bool {
 				if (set.emplace(std::move(val)).second) {
 					return true;
 				}
-				return warn_or_error(warn, "Duplicate set entry: \"", val, "\"");
+				Logger::warn_or_error(warn, "Duplicate set entry: \"", val, "\"");
+				return warn;
 			};
 		}
 
@@ -497,7 +489,8 @@ namespace OpenVic {
 				if (set.emplace(&val).second) {
 					return true;
 				}
-				return warn_or_error(warn, "Duplicate set entry: \"", &val, "\"");
+				Logger::warn_or_error(warn, "Duplicate set entry: \"", &val, "\"");
+				return warn;
 			};
 		}
 
@@ -509,7 +502,8 @@ namespace OpenVic {
 				if (map.emplace(key, std::move(value)).second) {
 					return true;
 				}
-				return warn_or_error(warn, "Duplicate map entry with key: \"", key, "\"");
+				Logger::warn_or_error(warn, "Duplicate map entry with key: \"", key, "\"");
+				return warn;
 			};
 		}
 	}
diff --git a/src/openvic-simulation/history/DiplomaticHistory.cpp b/src/openvic-simulation/history/DiplomaticHistory.cpp
index 55d6d6b..22ee765 100644
--- a/src/openvic-simulation/history/DiplomaticHistory.cpp
+++ b/src/openvic-simulation/history/DiplomaticHistory.cpp
@@ -32,20 +32,20 @@ AllianceHistory::AllianceHistory(
 	Country const* new_first,
 	Country const* new_second,
 	const Period new_period
-) : first { new_first }, second { new_second }, period {new_period} {}
+) : first { new_first }, second { new_second }, period { new_period } {}
 
 ReparationsHistory::ReparationsHistory(
 	Country const* new_receiver,
 	Country const* new_sender,
 	const Period new_period
-) : receiver { new_receiver }, sender { new_sender }, period {new_period} {}
+) : receiver { new_receiver }, sender { new_sender }, period { new_period } {}
 
 SubjectHistory::SubjectHistory(
 	Country const* new_overlord,
 	Country const* new_subject,
 	const type_t new_type,
 	const Period new_period
-) : overlord { new_overlord }, subject { new_subject }, type { new_type }, period {new_period} {}
+) : overlord { new_overlord }, subject { new_subject }, type { new_type }, period { new_period } {}
 
 void DiplomaticHistoryManager::reserve_more_wars(size_t size) {
 	if (locked) {
@@ -115,10 +115,10 @@ bool DiplomaticHistoryManager::load_diplomacy_history_file(CountryManager const&
 			std::optional<Date> end {};
 
 			bool ret = expect_dictionary_keys(
-				"first", ONE_EXACTLY, expect_identifier_or_string(country_manager.expect_country_str(assign_variable_callback_pointer(first))),
-				"second", ONE_EXACTLY, expect_identifier_or_string(country_manager.expect_country_str(assign_variable_callback_pointer(second))),
-				"start_date", ONE_EXACTLY, expect_identifier_or_string(expect_date_str(assign_variable_callback(start))),
-				"end_date", ZERO_OR_ONE, expect_identifier_or_string(expect_date_str(assign_variable_callback(end)))
+				"first", ONE_EXACTLY, country_manager.expect_country_identifier_or_string(assign_variable_callback_pointer(first)),
+				"second", ONE_EXACTLY, country_manager.expect_country_identifier_or_string(assign_variable_callback_pointer(second)),
+				"start_date", ONE_EXACTLY, expect_date_identifier_or_string(assign_variable_callback(start)),
+				"end_date", ZERO_OR_ONE, expect_date_identifier_or_string(assign_variable_callback(end))
 			)(node);
 
 			alliances.push_back({ first, second, { start, end } });
@@ -131,10 +131,10 @@ bool DiplomaticHistoryManager::load_diplomacy_history_file(CountryManager const&
 			std::optional<Date> end {};
 
 			bool ret = expect_dictionary_keys(
-				"first", ONE_EXACTLY, expect_identifier_or_string(country_manager.expect_country_str(assign_variable_callback_pointer(overlord))),
-				"second", ONE_EXACTLY, expect_identifier_or_string(country_manager.expect_country_str(assign_variable_callback_pointer(subject))),
-				"start_date", ONE_EXACTLY, expect_identifier_or_string(expect_date_str(assign_variable_callback(start))),
-				"end_date", ZERO_OR_ONE, expect_identifier_or_string(expect_date_str(assign_variable_callback(end)))
+				"first", ONE_EXACTLY, country_manager.expect_country_identifier_or_string(assign_variable_callback_pointer(overlord)),
+				"second", ONE_EXACTLY, country_manager.expect_country_identifier_or_string(assign_variable_callback_pointer(subject)),
+				"start_date", ONE_EXACTLY, expect_date_identifier_or_string(assign_variable_callback(start)),
+				"end_date", ZERO_OR_ONE, expect_date_identifier_or_string(assign_variable_callback(end))
 			)(node);
 
 			subjects.push_back({ overlord, subject, SubjectHistory::type_t::VASSAL, { start, end } });
@@ -147,10 +147,10 @@ bool DiplomaticHistoryManager::load_diplomacy_history_file(CountryManager const&
 			std::optional<Date> end {};
 
 			bool ret = expect_dictionary_keys(
-				"first", ONE_EXACTLY, country_manager.expect_country_identifier(assign_variable_callback_pointer(overlord)),
-				"second", ONE_EXACTLY, country_manager.expect_country_identifier(assign_variable_callback_pointer(subject)),
-				"start_date", ONE_EXACTLY, expect_date(assign_variable_callback(start)),
-				"end_date", ZERO_OR_ONE, expect_date(assign_variable_callback(end))
+				"first", ONE_EXACTLY, country_manager.expect_country_identifier_or_string(assign_variable_callback_pointer(overlord)),
+				"second", ONE_EXACTLY, country_manager.expect_country_identifier_or_string(assign_variable_callback_pointer(subject)),
+				"start_date", ONE_EXACTLY, expect_date_identifier_or_string(assign_variable_callback(start)),
+				"end_date", ZERO_OR_ONE, expect_date_identifier_or_string(assign_variable_callback(end))
 			)(node);
 
 			subjects.push_back({ overlord, subject, SubjectHistory::type_t::UNION, { start, end } });
@@ -163,10 +163,10 @@ bool DiplomaticHistoryManager::load_diplomacy_history_file(CountryManager const&
 			std::optional<Date> end {};
 
 			bool ret = expect_dictionary_keys(
-				"first", ONE_EXACTLY, country_manager.expect_country_identifier(assign_variable_callback_pointer(overlord)),
-				"second", ONE_EXACTLY, country_manager.expect_country_identifier(assign_variable_callback_pointer(subject)),
-				"start_date", ONE_EXACTLY, expect_date(assign_variable_callback(start)),
-				"end_date", ZERO_OR_ONE, expect_date(assign_variable_callback(end))
+				"first", ONE_EXACTLY, country_manager.expect_country_identifier_or_string(assign_variable_callback_pointer(overlord)),
+				"second", ONE_EXACTLY, country_manager.expect_country_identifier_or_string(assign_variable_callback_pointer(subject)),
+				"start_date", ONE_EXACTLY, expect_date_identifier_or_string(assign_variable_callback(start)),
+				"end_date", ZERO_OR_ONE, expect_date_identifier_or_string(assign_variable_callback(end))
 			)(node);
 
 			subjects.push_back({ overlord, subject, SubjectHistory::type_t::SUBSTATE, { start, end } });
@@ -179,10 +179,10 @@ bool DiplomaticHistoryManager::load_diplomacy_history_file(CountryManager const&
 			std::optional<Date> end {};
 
 			bool ret = expect_dictionary_keys(
-				"first", ONE_EXACTLY, country_manager.expect_country_identifier(assign_variable_callback_pointer(receiver)),
-				"second", ONE_EXACTLY, country_manager.expect_country_identifier(assign_variable_callback_pointer(sender)),
-				"start_date", ONE_EXACTLY, expect_date(assign_variable_callback(start)),
-				"end_date", ZERO_OR_ONE, expect_date(assign_variable_callback(end))
+				"first", ONE_EXACTLY, country_manager.expect_country_identifier_or_string(assign_variable_callback_pointer(receiver)),
+				"second", ONE_EXACTLY, country_manager.expect_country_identifier_or_string(assign_variable_callback_pointer(sender)),
+				"start_date", ONE_EXACTLY, expect_date_identifier_or_string(assign_variable_callback(start)),
+				"end_date", ZERO_OR_ONE, expect_date_identifier_or_string(assign_variable_callback(end))
 			)(node);
 
 			reparations.push_back({ receiver, sender, { start, end } });
diff --git a/src/openvic-simulation/history/Period.cpp b/src/openvic-simulation/history/Period.cpp
index cb133dd..37758a1 100644
--- a/src/openvic-simulation/history/Period.cpp
+++ b/src/openvic-simulation/history/Period.cpp
@@ -5,7 +5,7 @@ using namespace OpenVic;
 Period::Period(
 	const Date new_start_date,
 	const std::optional<Date> new_end_date
-) : start_date {new_start_date}, end_date {new_end_date} {}
+) : start_date { new_start_date }, end_date { new_end_date } {}
 
 bool Period::is_date_in_period(const Date date) const {
 	return start_date <= date && (!end_date.has_value() || end_date.value() >= date);
diff --git a/src/openvic-simulation/map/Map.cpp b/src/openvic-simulation/map/Map.cpp
index 9a97143..a5cd6a6 100644
--- a/src/openvic-simulation/map/Map.cpp
+++ b/src/openvic-simulation/map/Map.cpp
@@ -80,7 +80,7 @@ Province::distance_t Map::calculate_distance_between(Province const& from, Provi
 		)
 	);
 
-	return fvec2_t { min_x, to_pos.y - from_pos.y}.length_squared().sqrt();
+	return fvec2_t { min_x, to_pos.y - from_pos.y }.length_squared().sqrt();
 }
 
 using adjacency_t = Province::adjacency_t;
diff --git a/src/openvic-simulation/military/Deployment.cpp b/src/openvic-simulation/military/Deployment.cpp
index 14640ec..4e2693d 100644
--- a/src/openvic-simulation/military/Deployment.cpp
+++ b/src/openvic-simulation/military/Deployment.cpp
@@ -80,7 +80,7 @@ bool DeploymentManager::load_oob_file(
 
 			bool ret = expect_dictionary_keys(
 				"name", ONE_EXACTLY, expect_identifier_or_string(assign_variable_callback(leader_name)),
-				"date", ONE_EXACTLY, expect_identifier_or_string(expect_date_str(assign_variable_callback(leader_date))),
+				"date", ONE_EXACTLY, expect_date_identifier_or_string(assign_variable_callback(leader_date)),
 				"type", ONE_EXACTLY, UnitManager::expect_branch_identifier(assign_variable_callback(leader_branch)),
 				"personality", ONE_EXACTLY,
 					game_manager.get_military_manager().get_leader_trait_manager().expect_leader_trait_identifier_or_string(
diff --git a/src/openvic-simulation/misc/Define.cpp b/src/openvic-simulation/misc/Define.cpp
index e4e6b52..9ec5d49 100644
--- a/src/openvic-simulation/misc/Define.cpp
+++ b/src/openvic-simulation/misc/Define.cpp
@@ -95,9 +95,7 @@ bool DefineManager::load_defines_file(ast::NodeCPtr root) {
 
 			} else if (key == "start_date" || key == "end_date") {
 
-				return expect_identifier_or_string(expect_date_str(
-					std::bind_front(&DefineManager::add_date_define, this, key)
-				))(value);
+				return expect_date_identifier_or_string(std::bind_front(&DefineManager::add_date_define, this, key))(value);
 
 			} else {
 				return false;
diff --git a/src/openvic-simulation/scripts/Condition.cpp b/src/openvic-simulation/scripts/Condition.cpp
index 045649b..aab8d93 100644
--- a/src/openvic-simulation/scripts/Condition.cpp
+++ b/src/openvic-simulation/scripts/Condition.cpp
@@ -620,7 +620,7 @@ node_callback_t ConditionManager::expect_condition_node(
 			} else if (identifier == "relation") {
 				expect_pair("who", "value"); // { who = [tag/this/from] value = x }
 			} else if (identifier == "unemployment_by_type") {
-				expect_pair("type", "value"); // {type = [poptype] value = x }
+				expect_pair("type", "value"); // { type = [poptype] value = x }
 			} else if (identifier == "upper_house") {
 				expect_pair("ideology", "value"); // { ideology = name value = 0.x }
 			} else if (identifier == "work_available") {
diff --git a/src/openvic-simulation/types/Colour.hpp b/src/openvic-simulation/types/Colour.hpp
index 06a6b36..304d9de 100644
--- a/src/openvic-simulation/types/Colour.hpp
+++ b/src/openvic-simulation/types/Colour.hpp
@@ -12,7 +12,6 @@
 #include <type_traits>
 #include <utility>
 
-#include "openvic-simulation/utility/Getters.hpp"
 #include "openvic-simulation/utility/Utility.hpp"
 
 namespace OpenVic {
@@ -105,7 +104,10 @@ namespace OpenVic {
 
 	/* Colour represented by an unsigned integer, either 24-bit RGB or 32-bit ARGB. */
 	template<typename ValueT, typename ColourIntT, typename ColourTraits = colour_traits<ValueT, ColourIntT>>
-	struct basic_colour_t : ReturnByValueProperty {
+	struct basic_colour_t {
+		/* PROPERTY generated getter functions will return colours by value, rather than const reference. */
+		using ov_return_by_value = void;
+
 		using colour_traits = ColourTraits;
 		using value_type = typename colour_traits::value_type;
 		using integer_type = typename colour_traits::integer_type;
diff --git a/src/openvic-simulation/types/Date.hpp b/src/openvic-simulation/types/Date.hpp
index 9178e6e..9376293 100644
--- a/src/openvic-simulation/types/Date.hpp
+++ b/src/openvic-simulation/types/Date.hpp
@@ -1,16 +1,19 @@
 #pragma once
 
 #include <algorithm>
+#include <array>
 #include <cstdint>
 #include <ostream>
 #include <string>
 
-#include "openvic-simulation/utility/Getters.hpp"
 #include "openvic-simulation/utility/Utility.hpp"
 
 namespace OpenVic {
 	// A relative period between points in time, measured in days
-	struct Timespan : ReturnByValueProperty {
+	struct Timespan {
+		/* PROPERTY generated getter functions will return timespans by value, rather than const reference. */
+		using ov_return_by_value = void;
+
 		using day_t = int64_t;
 
 	private:
@@ -86,7 +89,10 @@ namespace OpenVic {
 
 	// Represents an in-game date
 	// Note: Current implementation does not account for leap-years, or dates before Year 0
-	struct Date : ReturnByValueProperty {
+	struct Date {
+		/* PROPERTY generated getter functions will return dates by value, rather than const reference. */
+		using ov_return_by_value = void;
+
 		using year_t = uint16_t;
 		using month_t = uint8_t;
 		using day_t = uint8_t;
diff --git a/src/openvic-simulation/types/IdentifierRegistry.hpp b/src/openvic-simulation/types/IdentifierRegistry.hpp
index 7e6fdb3..f1edc95 100644
--- a/src/openvic-simulation/types/IdentifierRegistry.hpp
+++ b/src/openvic-simulation/types/IdentifierRegistry.hpp
@@ -269,30 +269,39 @@ namespace OpenVic {
 		} \
 	} \
 	constexpr NodeTools::Callback<std::string_view> auto expect_item_str( \
-		NodeTools::Callback<external_value_type CONST&> auto callback, bool warn \
+		NodeTools::Callback<external_value_type CONST&> auto callback, bool allow_empty, bool warn \
 	) CONST { \
-		return [this, callback, warn](std::string_view identifier) -> bool { \
+		return [this, callback, allow_empty, warn](std::string_view identifier) -> bool { \
+			if (identifier.empty()) { \
+				if (allow_empty) { \
+					return true; \
+				} else { \
+					Logger::warn_or_error(warn, "Invalid ", name, " identifier: empty!"); \
+					return warn; \
+				} \
+			} \
 			external_value_type CONST* item = get_item_by_identifier(identifier); \
 			if (item != nullptr) { \
 				return callback(*item); \
 			} \
-			return NodeTools::warn_or_error(warn, "Invalid ", name, " identifier: ", identifier); \
+			Logger::warn_or_error(warn, "Invalid ", name, " identifier: ", identifier); \
+			return warn; \
 		}; \
 	} \
 	constexpr NodeTools::NodeCallback auto expect_item_identifier( \
 		NodeTools::Callback<external_value_type CONST&> auto callback, bool warn \
 	) CONST { \
-		return NodeTools::expect_identifier(expect_item_str(callback, warn)); \
+		return NodeTools::expect_identifier(expect_item_str(callback, false, warn)); \
 	} \
 	constexpr NodeTools::NodeCallback auto expect_item_string( \
-		NodeTools::Callback<external_value_type CONST&> auto callback, bool warn \
+		NodeTools::Callback<external_value_type CONST&> auto callback, bool allow_empty, bool warn \
 	) CONST { \
-		return NodeTools::expect_string(expect_item_str(callback, warn)); \
+		return NodeTools::expect_string(expect_item_str(callback, allow_empty, warn), allow_empty); \
 	} \
 	constexpr NodeTools::NodeCallback auto expect_item_identifier_or_string( \
-		NodeTools::Callback<external_value_type CONST&> auto callback, bool warn \
+		NodeTools::Callback<external_value_type CONST&> auto callback, bool allow_empty, bool warn \
 	) CONST { \
-		return NodeTools::expect_identifier_or_string(expect_item_str(callback, warn)); \
+		return NodeTools::expect_identifier_or_string(expect_item_str(callback, allow_empty, warn), allow_empty); \
 	} \
 	constexpr NodeTools::NodeCallback auto expect_item_assign_and_default( \
 		NodeTools::KeyValueCallback auto default_callback, \
@@ -541,9 +550,10 @@ private:
 		return registry.get_items(); \
 	} \
 	constexpr NodeTools::Callback<std::string_view> auto expect_##singular##_str( \
-		NodeTools::Callback<decltype(registry)::external_value_type const_kw&> auto callback, bool warn = false \
+		NodeTools::Callback<decltype(registry)::external_value_type const_kw&> auto callback, bool allow_empty = false, \
+		bool warn = false \
 	) const_kw { \
-		return registry.expect_item_str(callback, warn); \
+		return registry.expect_item_str(callback, allow_empty, warn); \
 	} \
 	constexpr NodeTools::NodeCallback auto expect_##singular##_identifier( \
 		NodeTools::Callback<decltype(registry)::external_value_type const_kw&> auto callback, bool warn = false \
@@ -551,14 +561,16 @@ private:
 		return registry.expect_item_identifier(callback, warn); \
 	} \
 	constexpr NodeTools::NodeCallback auto expect_##singular##_string( \
-		NodeTools::Callback<decltype(registry)::external_value_type const_kw&> auto callback, bool warn = false \
+		NodeTools::Callback<decltype(registry)::external_value_type const_kw&> auto callback, bool allow_empty = false, \
+		bool warn = false \
 	) const_kw { \
-		return registry.expect_item_string(callback, warn); \
+		return registry.expect_item_string(callback, allow_empty, warn); \
 	} \
 	constexpr NodeTools::NodeCallback auto expect_##singular##_identifier_or_string( \
-		NodeTools::Callback<decltype(registry)::external_value_type const_kw&> auto callback, bool warn = false \
+		NodeTools::Callback<decltype(registry)::external_value_type const_kw&> auto callback,bool allow_empty = false, \
+		bool warn = false \
 	) const_kw { \
-		return registry.expect_item_identifier_or_string(callback, warn); \
+		return registry.expect_item_identifier_or_string(callback, allow_empty, warn); \
 	} \
 	constexpr NodeTools::NodeCallback auto expect_##singular##_assign_and_default( \
 		NodeTools::KeyValueCallback auto default_callback, \
diff --git a/src/openvic-simulation/types/Vector.hpp b/src/openvic-simulation/types/Vector.hpp
index 5514cc3..6897835 100644
--- a/src/openvic-simulation/types/Vector.hpp
+++ b/src/openvic-simulation/types/Vector.hpp
@@ -6,6 +6,9 @@ namespace OpenVic {
 
 	template<typename T>
 	struct vec2_t {
+		/* PROPERTY generated getter functions will return 2D vectors by value, rather than const reference. */
+		using ov_return_by_value = void;
+
 		using type = T;
 
 		T x, y;
diff --git a/src/openvic-simulation/types/fixed_point/FixedPoint.hpp b/src/openvic-simulation/types/fixed_point/FixedPoint.hpp
index 8d3a74b..6a47194 100644
--- a/src/openvic-simulation/types/fixed_point/FixedPoint.hpp
+++ b/src/openvic-simulation/types/fixed_point/FixedPoint.hpp
@@ -1,22 +1,21 @@
 #pragma once
 
-#include <cerrno>
-#include <cmath>
 #include <cstdint>
 #include <cstdlib>
 #include <limits>
 #include <sstream>
 #include <string_view>
 
-#include "openvic-simulation/utility/Getters.hpp"
+#include "openvic-simulation/types/fixed_point/FixedPointLUT.hpp"
 #include "openvic-simulation/utility/Logger.hpp"
 #include "openvic-simulation/utility/NumberUtils.hpp"
 #include "openvic-simulation/utility/StringUtils.hpp"
 
-#include "FixedPointLUT.hpp"
-
 namespace OpenVic {
-	struct fixed_point_t : ReturnByValueProperty {
+	struct fixed_point_t {
+		/* PROPERTY generated getter functions will return fixed points by value, rather than const reference. */
+		using ov_return_by_value = void;
+
 		static constexpr size_t SIZE = 8;
 
 		static constexpr int32_t PRECISION = FPLUT::SIN_LUT_PRECISION;
@@ -27,7 +26,7 @@ namespace OpenVic {
 		constexpr fixed_point_t(int32_t new_value) : value { static_cast<int64_t>(new_value) << PRECISION } {}
 
 		// Trivial destructor
-		~fixed_point_t() = default;
+		constexpr ~fixed_point_t() = default;
 
 		static constexpr fixed_point_t max() {
 			return std::numeric_limits<int64_t>::max();
diff --git a/src/openvic-simulation/types/fixed_point/FixedPointLUT.hpp b/src/openvic-simulation/types/fixed_point/FixedPointLUT.hpp
index 45cb639..a5d585f 100644
--- a/src/openvic-simulation/types/fixed_point/FixedPointLUT.hpp
+++ b/src/openvic-simulation/types/fixed_point/FixedPointLUT.hpp
@@ -1,15 +1,10 @@
 #pragma once
 
-#include <array>
-#include <cmath>
-#include <cstddef>
 #include <cstdint>
-#include <numbers>
-#include <utility>
 
 namespace OpenVic::FPLUT {
 
-#include "FixedPointLUT_sin.hpp"
+#include "openvic-simulation/types/fixed_point/FixedPointLUT_sin.hpp"
 
 	constexpr int32_t SHIFT = SIN_LUT_PRECISION - SIN_LUT_COUNT_LOG2;
 
diff --git a/src/openvic-simulation/types/fixed_point/FixedPointMath.hpp b/src/openvic-simulation/types/fixed_point/FixedPointMath.hpp
index c0b5f42..6cdb926 100644
--- a/src/openvic-simulation/types/fixed_point/FixedPointMath.hpp
+++ b/src/openvic-simulation/types/fixed_point/FixedPointMath.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "FixedPoint.hpp"
+#include "openvic-simulation/types/fixed_point/FixedPoint.hpp"
 
 namespace OpenVic::FPMath {
 	constexpr fixed_point_t sin(fixed_point_t number) {
diff --git a/src/openvic-simulation/utility/Getters.hpp b/src/openvic-simulation/utility/Getters.hpp
index 33aa5a2..fa76e74 100644
--- a/src/openvic-simulation/utility/Getters.hpp
+++ b/src/openvic-simulation/utility/Getters.hpp
@@ -51,13 +51,15 @@ public: \
 ACCESS:
 
 namespace OpenVic {
-	/* Any struct extending ReturnByValueProperty will be returned by value by PROPERTY-generated getter functions,
+	/* Any struct tagged with ov_return_by_value will be returned by value by PROPERTY-generated getter functions,
 	 * instead of by const reference as structs are by default. Use this for small structs which don't contain any
-	 * dynamically allocated memory, e.g. Date and fixed_point_t. */
-	struct ReturnByValueProperty {
-		constexpr bool operator==(ReturnByValueProperty const&) const = default;
-		constexpr std::strong_ordering operator<=>(ReturnByValueProperty const&) const = default;
-	};
+	 * dynamically allocated memory, e.g. dates and colours. The tag must be public, as in the example below:
+	 *
+	 * public:
+	 *     using ov_return_by_value = void;
+	 */
+	template<typename T>
+	concept ReturnByValue = requires { typename T::ov_return_by_value; };
 
 	/*
 	 * Template function used to choose the return type and provide the implementation
@@ -72,7 +74,7 @@ namespace OpenVic {
 			/* Return std::string_view looking at std::string */
 			return std::string_view { property };
 		} else if constexpr (
-			std::integral<T> || std::floating_point<T> || std::is_enum_v<T> || std::derived_from<T, ReturnByValueProperty>
+			std::integral<T> || std::floating_point<T> || std::is_enum_v<T> || ReturnByValue<T>
 		) {
 			/* Return value */
 			return T { property };
diff --git a/src/openvic-simulation/utility/Logger.hpp b/src/openvic-simulation/utility/Logger.hpp
index 53decb3..7a2c3d0 100644
--- a/src/openvic-simulation/utility/Logger.hpp
+++ b/src/openvic-simulation/utility/Logger.hpp
@@ -75,16 +75,16 @@ namespace OpenVic {
 			size_t message_count;
 		};
 
-		template<typename... Ts>
+		template<typename... Args>
 		struct log {
-			log(log_channel_t& log_channel, Ts&&... ts, source_location const& location) {
+			log(log_channel_t& log_channel, Args&&... args, source_location const& location) {
 				std::stringstream stream;
 				stream << StringUtils::get_filename(location.file_name()) << "("
 					/* Function name removed to reduce clutter. It is already included
 					* in Godot's print functions, so this was repeating it. */
 					//<< location.line() << ") `" << location.function_name() << "`: ";
 					<< location.line() << "): ";
-				((stream << std::forward<Ts>(ts)), ...);
+				((stream << std::forward<Args>(args)), ...);
 				stream << std::endl;
 				log_channel.queue.push(stream.str());
 				if (log_channel.func) {
@@ -109,19 +109,28 @@ public: \
 	static inline size_t get_##name##_count() { \
 		return name##_channel.message_count; \
 	} \
-	template<typename... Ts> \
+	template<typename... Args> \
 	struct name { \
-		name(Ts&&... ts, source_location const& location = source_location::current()) { \
-			log<Ts...> { name##_channel, std::forward<Ts>(ts)..., location }; \
+		name(Args&&... args, source_location const& location = source_location::current()) { \
+			log<Args...> { name##_channel, std::forward<Args>(args)..., location }; \
 		} \
 	}; \
-	template<typename... Ts> \
-	name(Ts&&...) -> name<Ts...>;
+	template<typename... Args> \
+	name(Args&&...) -> name<Args...>;
 
 		LOG_FUNC(info)
 		LOG_FUNC(warning)
 		LOG_FUNC(error)
 
 #undef LOG_FUNC
+
+		template<typename... Args>
+		static inline constexpr void warn_or_error(bool warn, Args&&... args) {
+			if (warn) {
+				warning(std::forward<Args>(args)...);
+			} else {
+				error(std::forward<Args>(args)...);
+			}
+		}
 	};
 }