Improved

Author: sajith

CMakeLists.txt

@@ -22,4 +22,5 @@ set(CMAKE_CXX_STANDARD 20)
 #add_executable(lspqueryset LSP/lsp_query_set.cpp)
 #add_executable(isp_door ISP/isp_door_example.cpp)
 #add_executable(isp_door_better ISP/isp_door_example_better.cpp)
-add_executable(isp_door_better2 ISP/isp_door_example_better2.cpp)
+#add_executable(isp_door_better2 ISP/isp_door_example_better2.cpp)
+add_executable(isp_device ISP/isp_device_example.cpp)

ISP/isp_device_example.cpp

@@ -0,0 +1,88 @@
+//
+// Created by sajith on 4/19/21.
+//
+
+#include <iostream>
+#include <stdexcept>
+
+class Device
+{
+public:
+    virtual ~Device() = default;
+    virtual void print() = 0;
+    virtual void scan() = 0;
+    virtual void fax() = 0;
+};
+
+
+class AdvancedPrinter : public Device
+{
+
+public:
+
+    void print()
+    {
+        std::cout << "Printing...\n";
+    }
+
+    void scan()
+    {
+        std::cout << "Scanning...\n";
+    }
+
+    void fax()
+    {
+        std::cout << "Faxing...\n";
+    }
+};
+
+
+class SimplePrinter : public Device
+{
+
+public:
+
+    void print()
+    {
+        std::cout << "Printing...\n";
+    }
+
+    void scan()
+    {
+        throw std::runtime_error{"Not implemented"};
+    }
+
+    void fax()
+    {
+        throw std::runtime_error{"Not implemented"};
+    }
+};
+
+// clients
+void printUsers(Device &device)
+{
+    device.print();
+}
+
+void scanUsers(Device &device)
+{
+    device.scan();
+}
+
+void faxUsers(Device &device)
+{
+    device.fax();
+}
+
+int main()
+{
+    AdvancedPrinter advancedPrinter;
+    SimplePrinter simplePrinter;
+
+    printUsers(advancedPrinter);
+    scanUsers(advancedPrinter);
+    faxUsers(advancedPrinter);
+
+    scanUsers(simplePrinter);
+    return 0;
+}