LazyGlobal

Will help us avoid SIOF

Bigfoot/Libs/Utils/Include/Utils/LazyGlobal.hpp

@@ -0,0 +1,40 @@
+/*********************************************************************
+ * \file   LazyGlobal.hpp
+ *
+ * \author Romain BOULLARD
+ * \date   September 2026
+ *********************************************************************/
+#ifndef BIGFOOT_UTILS_LAZYGLOBAL_HPP
+#define BIGFOOT_UTILS_LAZYGLOBAL_HPP
+#include <type_traits>
+
+namespace Bigfoot
+{
+template<class TYPE, class TAG = TYPE>
+    requires std::is_default_constructible_v<TYPE>
+class LazyGlobal
+{
+  public:
+    [[nodiscard]]
+    TYPE* operator->() const
+    {
+        return &Get();
+    }
+
+    [[nodiscard]]
+    operator TYPE*() const
+    {
+        return &Get();
+    }
+
+  private:
+    [[nodiscard]]
+    static TYPE& Get()
+    {
+        static TYPE instance;
+        return instance;
+    }
+};
+}   // namespace Bigfoot
+
+#endif

Bigfoot/Tests/Utils/LazyGlobal.cpp

@@ -0,0 +1,72 @@
+/*********************************************************************
+ * \file   LazyGlobal.cpp
+ *
+ * \author Romain BOULLARD
+ * \date   September 2026
+ *********************************************************************/
+#include <Utils/LazyGlobal.hpp>
+
+#include <gtest/gtest.h>
+
+#include <cstdint>
+
+namespace Bigfoot
+{
+class DummyValue
+{
+  public:
+    [[nodiscard]]
+    std::uint32_t GetValue() const
+    {
+        return m_value;
+    }
+
+    void SetValue(const std::uint32_t p_value)
+    {
+        m_value = p_value;
+    }
+
+  private:
+    std::uint32_t m_value = 0;
+};
+
+/****************************************************************************************/
+
+class LazyGlobalFixture: public ::testing::Test
+{
+  protected:
+};
+
+LazyGlobal<DummyValue> g_dummyValueA;
+LazyGlobal<DummyValue, class DummyValueA> g_dummyValueB;
+
+/****************************************************************************************/
+
+TEST_F(LazyGlobalFixture, ArrowOperator)
+{
+    g_dummyValueA->SetValue(42);
+
+    EXPECT_EQ(g_dummyValueA->GetValue(), 42);
+}
+
+/****************************************************************************************/
+
+TEST_F(LazyGlobalFixture, PointerConversion)
+{
+    DummyValue* const pointer = g_dummyValueA;
+    pointer->SetValue(7);
+
+    EXPECT_EQ(g_dummyValueA->GetValue(), 7);
+}
+
+/****************************************************************************************/
+
+TEST_F(LazyGlobalFixture, DifferentTags_ShouldYieldIndependentInstancesOfTheSameType)
+{
+    g_dummyValueA->SetValue(1);
+    g_dummyValueB->SetValue(2);
+
+    EXPECT_EQ(g_dummyValueA->GetValue(), 1);
+    EXPECT_EQ(g_dummyValueB->GetValue(), 2);
+}
+}   // namespace Bigfoot