Hands‑On Python Projects: From Instant Tagging to XML‑Driven Site Generators

Python is a highly readable, general‑purpose programming language whose name was inspired by the British comedy group Monty Python; it aims to be fun to use, easy to set up, and provides immediate feedback, making it an excellent choice for beginners.

As a multi‑paradigm language supporting scripting and object‑oriented styles, Python is widely adopted in industry by organizations such as NASA and Industrial Light & Magic, offering great potential for developers seeking versatile tools.

Python Project Exercise 1: Instant Tagging

The project follows the "Python Basics Tutorial" and is divided into four modules after refactoring: a handler module that outputs fixed HTML tags, a filter module that uses regular expressions, a rule module that defines condition and action methods, and a parser module that coordinates rules and filters.

The handler module provides start and end tags with a friendly interface.

The filter module consists of three regular‑expression filters: emphasis, URL, and email.

The rule module implements condition to test strings and action to invoke the handler for output.

Utility functions are collected in utils.py.

The parser module stores lists of rules and filters, enabling a plug‑in architecture that greatly improves flexibility.

Python Project Exercise 2: Drawing a Nice Picture

This project demonstrates PDF manipulation using urllib and the reportlab library. It shows how Python’s list comprehensions can embed loops directly inside array brackets for concise code.

Example code is illustrated in the following image.

Python Project Exercise 3: Universal XML

This project generates a static website from an XML description (e.g., website.xml). It parses XML using either SAX (for speed and low memory usage) or DOM (for full‑document access).

Key steps include importing xml.sax.parse and a custom ContentHandler, then handling startElement, endElement, and characters callbacks to build HTML pages and directories.

The XML structure contains only page and directory nodes, guiding the creation of files and folders.

Implementation details are shown in the image below.

The program uses a dispatch mechanism to map XML tags to corresponding handler functions (e.g., startPage, defaultStart), creating a public_html directory with the generated site.

Python Project Exercise 4: News Aggregator

This script aggregates news from Usenet newsgroups, storing the results as plain‑text or HTML files, similar to modern RSS readers.

The core component is NewsAgent, which manages sources ( NNTPSource, SimpleWebSource) and destinations ( PlainDestination, HTMLDestination). The main program registers sources and destinations, demonstrating a layered architecture.

Key classes and their responsibilities are illustrated below.