2 1 Classes To Interfaces

Summary

This video demonstrates the challenges of replacing one service provider (class) with another in a C++ application. The instructor highlights the need to change class names, function names, and update linked libraries when switching services. The focus is on the difficulty of refactoring large portions of code when these changes are required, with a real-world analogy to switching service providers. The key takeaway is the importance of designing software systems that allow for easy service replacements with minimal code changes, ensuring flexibility and maintainability in the long run.

Takeaways

• 😀 Switching from one class or service implementation to another may require changing both the class name and function names in your code.
• 😀 Even a small change in service provider can lead to multiple code modifications, highlighting the need for maintainable architecture.
• 😀 Creating a new shared library (DLL) involves linking it properly in the console application to use its classes and functions.
• 😀 Export macros in DLLs (e.g., ANOTHER_SHARED_LIBRARY_EXPORTS) must be correctly defined, but Visual Studio handles this automatically during compilation.
• 😀 Building the new library first and then rebuilding the console application ensures that the updated service is correctly integrated.
• 😀 Directly hardcoding class names makes code difficult to maintain and adapt when services change.
• 😀 In large applications, even minor changes can become significant, making it important to design for easy service replacement.
• 😀 Proper architectural planning allows seamless switching between different service providers without extensive code rewrites.
• 😀 The real-world analogy: switching a service provider should be as easy as replacing a SIM card; code should be designed similarly.
• 😀 The session emphasizes writing programs with future maintainability in mind, particularly focusing on dependency management and class architecture.
• 😀 Interface-based or abstract class designs can mitigate the issues shown by allowing new service implementations to integrate with minimal changes.

Q & A

What is the primary objective of this session?

The primary objective of the session is to illustrate how switching between service providers in programming can impact the code and how to design systems where such switches are easier to implement in real life.

Why do we need to switch from one service provider to another?

Switching between service providers is a common practice in programming and real life. It could be for reasons such as performance, cost, reliability, or functionality improvements. The objective is to make it easy to switch services without overhauling large parts of the code.

What changes are necessary when switching from one service provider class to another?

When switching from one service provider class to another, the class name, the function names, and possibly other code references will need to be updated throughout the application. This is necessary because different service providers may use different class names and function signatures.

What is the challenge when switching between service providers in the example?

The challenge is that 100% of the code may need to be rewritten to accommodate the different class and function names when switching from one service provider to another. This could mean making significant changes in many parts of the code, which can be time-consuming and error-prone.

How does the switch from 'HelloWorld' to 'AnotherHelloWorld' work in the example?

In the example, 'HelloWorld' is replaced by 'AnotherHelloWorld'. This involves updating the class and function names throughout the code. A new DLL file, 'anothersharedLibrary.lib', is created with the new class and function. After linking it in the application, the output will reflect the new service provider’s behavior.

What is the purpose of the 'AnotherSharedLibrary_exports' macro?

The 'AnotherSharedLibrary_exports' macro is used to define the export settings for the shared library. This macro is automatically defined by Visual Studio, ensuring that the correct functions and classes are exported when building the library.

What is the role of the 'Linker Input' in the switch process?

The 'Linker Input' is responsible for linking the application with the correct version of the shared library. When switching between service providers, the linker needs to be updated to reference the new shared library (in this case, 'anothersharedLibrary.lib').

What happens if you don't account for the need to switch service providers in your code architecture?

If you don’t design your code to handle easy switching of service providers, you may face significant problems. In large applications, even small changes could require updating hundreds or thousands of lines of code. This would increase the risk of errors and make maintenance more difficult.

What is the analogy used in the script to explain the difficulty of switching service providers?

The script uses the analogy of switching SIM cards between mobile network providers. In real life, changing service providers is often as simple as swapping out a SIM card, but in programming, switching service providers can require extensive code modifications unless the system is designed to accommodate such changes easily.

How can the architecture of a program be designed to make switching services easier?

The program's architecture should be flexible, with abstractions that allow for easy replacement of services. This includes defining clear interfaces for service providers, minimizing direct dependencies between components, and designing the system so that only minimal changes are needed when switching providers.