3 files changed, 12 insertions, 12 deletions
diff --git a/src/openvic/types/Colour.hpp b/src/openvic/types/Colour.hpp
index fdac40e..01f3852 100644
--- a/src/openvic/types/Colour.hpp
+++ b/src/openvic/types/Colour.hpp
@@ -2,6 +2,9 @@
 
 #include <algorithm>
 #include <cstdint>
+#include <iomanip>
+#include <sstream>
+#include <string>
 
 namespace OpenVic {
 	// Represents a 24-bit RGB integer OR a 32-bit ARGB integer
@@ -24,4 +27,10 @@ namespace OpenVic {
 	constexpr float colour_byte_to_float(colour_t colour) {
 		return std::clamp(static_cast<float>(colour) / 255.0f, 0.0f, 1.0f);
 	}
+
+	inline std::string colour_to_hex_string(colour_t colour) {
+		std::ostringstream stream;
+		stream << std::hex << std::setfill('0') << std::setw(6) << colour;
+		return stream.str();
+	}
 }
diff --git a/src/openvic/types/IdentifierRegistry.cpp b/src/openvic/types/IdentifierRegistry.cpp
index 3710387..6d5221b 100644
--- a/src/openvic/types/IdentifierRegistry.cpp
+++ b/src/openvic/types/IdentifierRegistry.cpp
@@ -1,8 +1,6 @@
 #include "IdentifierRegistry.hpp"
 
 #include <cassert>
-#include <iomanip>
-#include <sstream>
 
 using namespace OpenVic;
 
@@ -21,14 +19,8 @@ HasColour::HasColour(colour_t const new_colour, bool can_be_null) : colour(new_c
 
 colour_t HasColour::get_colour() const { return colour; }
 
-std::string HasColour::colour_to_hex_string(colour_t const colour) {
-	std::ostringstream stream;
-	stream << std::hex << std::setfill('0') << std::setw(6) << colour;
-	return stream.str();
-}
-
 std::string HasColour::colour_to_hex_string() const {
-	return colour_to_hex_string(colour);
+	return OpenVic::colour_to_hex_string(colour);
 }
 
 HasIdentifierAndColour::HasIdentifierAndColour(const std::string_view new_identifier,
diff --git a/src/openvic/types/IdentifierRegistry.hpp b/src/openvic/types/IdentifierRegistry.hpp
index 989db01..54b466e 100644
--- a/src/openvic/types/IdentifierRegistry.hpp
+++ b/src/openvic/types/IdentifierRegistry.hpp
@@ -1,7 +1,6 @@
 #pragma once
 
 #include <map>
-#include <unordered_map>
 #include <vector>
 
 #include "openvic/types/Colour.hpp"
@@ -46,7 +45,6 @@ namespace OpenVic {
 
 		colour_t get_colour() const;
 		std::string colour_to_hex_string() const;
-		static std::string colour_to_hex_string(colour_t const colour);
 	};
 
 	/*
@@ -74,7 +72,8 @@ namespace OpenVic {
 	 * the type of object that the registry will store, and the second part ensures
 	 * that HasIdentifier is a base class of T.
 	 */
-	template<class T, typename std::enable_if<std::is_base_of<HasIdentifier, T>::value>::type* = nullptr>
+	template<typename T>
+	requires(std::derived_from<T, HasIdentifier>)
 	class IdentifierRegistry {
 		using identifier_index_map_t = std::map<std::string, size_t, std::less<void>>;