From c93cdaf332f82a41272627e90361f40835d9b80a Mon Sep 17 00:00:00 2001
From: hop311 <hop3114@gmail.com>
Date: Mon, 15 Apr 2024 00:27:41 +0100
Subject: Add std::optional assign pointer callback with overwrite control

---
 src/openvic-simulation/dataloader/NodeTools.hpp | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

(limited to 'src/openvic-simulation/dataloader')

diff --git a/src/openvic-simulation/dataloader/NodeTools.hpp b/src/openvic-simulation/dataloader/NodeTools.hpp
index c41c09e..b99fc48 100644
--- a/src/openvic-simulation/dataloader/NodeTools.hpp
+++ b/src/openvic-simulation/dataloader/NodeTools.hpp
@@ -443,9 +443,17 @@ namespace OpenVic {
 			};
 		}
 
+		/* By default this will only allow an optional to be set once. Set allow_overwrite
+		 * to true to allow multiple assignments, with the last taking precedence. */
 		template<typename T>
-		Callback<T const&> auto assign_variable_callback_pointer(std::optional<T const*>& var) {
-			return [&var](T const& val) -> bool {
+		Callback<T const&> auto assign_variable_callback_pointer_opt(
+			std::optional<T const*>& var, bool allow_overwrite = false
+		) {
+			return [&var, allow_overwrite](T const& val) -> bool {
+				if (!allow_overwrite && var.has_value()) {
+					Logger::error("Canoot assign pointer value to already-initialised optional!");
+					return false;
+				}
 				var = &val;
 				return true;
 			};
-- 
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