Book Image

Advanced Python Programming

By : Dr. Gabriele Lanaro, Quan Nguyen, Sakis Kasampalis
Book Image

Advanced Python Programming

By: Dr. Gabriele Lanaro, Quan Nguyen, Sakis Kasampalis

Overview of this book

This Learning Path shows you how to leverage the power of both native and third-party Python libraries for building robust and responsive applications. You will learn about profilers and reactive programming, concurrency and parallelism, as well as tools for making your apps quick and efficient. You will discover how to write code for parallel architectures using TensorFlow and Theano, and use a cluster of computers for large-scale computations using technologies such as Dask and PySpark. With the knowledge of how Python design patterns work, you will be able to clone objects, secure interfaces, dynamically choose algorithms, and accomplish much more in high performance computing. By the end of this Learning Path, you will have the skills and confidence to build engaging models that quickly offer efficient solutions to your problems. This Learning Path includes content from the following Packt products: • Python High Performance - Second Edition by Gabriele Lanaro • Mastering Concurrency in Python by Quan Nguyen • Mastering Python Design Patterns by Sakis Kasampalis
Table of Contents (41 chapters)
Title Page
Copyright
About Packt
Contributors
Preface
Index

Implementation


There are many ways to implement a Chain of Responsibility in Python, but my favorite implementation is the one by Vespe Savikko (https://legacy.python.org/workshops/1997-10/proceedings/savikko.html). Vespe's implementation uses dynamic dispatching in a Pythonic style to handle requests (http://j.mp/ddispatch).

Let's implement a simple, event-based system using Vespe's implementation as a guide. The following is the UML class diagram of the system:

The Event class describes an event. We'll keep it simple, so in our case, an event has only a name:

class Event:
     def __init__(self, name):
         self.name = name

     def __str__(self):
         return self.name

The Widget class is the core class of the application. The parent aggregation shown in the UML diagram indicates that each widget can have a reference to a parent object, which by convention, we assume is a Widget instance. Note, however, that according to the rules of inheritance, an instance of any of the subclasses...