To conclude the book, let's summarize some of the key steps involved in designing an application. Depending on what you want to design, choose a suitable data structure to represent your needs logically. If required, combine primitive data structures to form complex structures such as, say, a list or a tuple of dictionaries. Create classes for objects that constitute your application. Add attributes that need to be manipulated and methods to manipulate these attributes. Manipulate attributes by using a different API provided by a rich set of Python-standard and external libraries.

We tried to build several applications in this book. Then, we had a look at an explanation for the code. However, when you try to explain a software development process in a sequential text, you sometimes mislead your readers by implying that
the development of software programs is a linear process. This is hardly true.

Actual programming doesn't usually work this way. In fact, small- to medium-sized programs are normally written in an incremental trial-and-error process, where assumptions get changed and structures are modified throughout the course of application development.

Here is how you would develop a small- to a medium-sized application:

1. Start with a simple script.
2. Set a small achievable goal, implement it, and then think of adding the next feature to your program in an incremental fashion.
3. You may or may not introduce a class structure initially. If you are clear about the problem domain, you may introduce the class structure from the very beginning.
4. If you are not initially sure about the class structure, start with simple procedural code. As your program starts to grow, you will probably start getting a lot of global variables. It is here that you will start getting an idea of the structural dimensions of your program. It is now time to refactor and restructure your program to introduce a class structure.
5. Harden your program against unanticipated runtime failures and edge cases to make it ready for production use.

That concludes the book. If you have any suggestions or feedback, please leave us a comment. If you found this book helpful, please rate it online and help us spread the word.