Unique Ptr

unique_ptr_basics/Makefile

@@ -0,0 +1,22 @@
+# shared compiler configuration
+include ../common.mk
+
+TARGET := unique_ptr_basics
+SRCS   := main.cpp
+OBJS   := $(SRCS:.cpp=.o)
+
+all: $(TARGET)
+
+$(TARGET): $(OBJS)
+	$(CXX) $(CXXFLAGS) -o $@ $^
+
+%.o: %.cpp
+	$(CXX) $(CXXFLAGS) -c $< -o $@
+
+run: $(TARGET)
+	./$(TARGET)
+
+clean:
+	rm -f $(OBJS) $(TARGET)
+
+.PHONY: all clean run

unique_ptr_basics/main.cpp

@@ -0,0 +1,64 @@
+#include <iostream>
+#include <memory>
+#include <utility>
+
+class Resource {
+public:
+    explicit Resource(int id) : id_(id) {
+        std::cout << "Resource " << id_ << " acquired\n";
+    }
+
+    ~Resource() {
+        std::cout << "Resource " << id_ << " released\n";
+    }
+
+    void use() const {
+        std::cout << "Using resource " << id_ << "\n";
+    }
+
+private:
+    int id_;
+};
+
+// Factory function: returns ownership
+std::unique_ptr<Resource> make_resource(int id) {
+    return std::make_unique<Resource>(id);
+}
+
+// Takes ownership explicitly
+void consume_resource(std::unique_ptr<Resource> res) {
+    std::cout << "Consuming resource\n";
+    res->use();
+    // res is destroyed here
+}
+
+// Borrows resource (no ownership transfer)
+void inspect_resource(const Resource& res) {
+    std::cout << "Inspecting resource\n";
+    res.use();
+}
+
+int main() {
+    std::cout << "=== create resource ===\n";
+    auto r1 = make_resource(1);
+
+    std::cout << "\n=== borrow resource ===\n";
+    inspect_resource(*r1);
+
+    std::cout << "\n=== move ownership ===\n";
+    auto r2 = std::move(r1);
+
+    if (!r1) {
+        std::cout << "r1 no longer owns the resource\n";
+    }
+
+    std::cout << "\n=== transfer ownership to function ===\n";
+    consume_resource(std::move(r2));
+
+    if (!r2) {
+        std::cout << "r2 no longer owns the resource\n";
+    }
+
+    std::cout << "\n=== end of program ===\n";
+    return 0;
+}