Build Real-World Python Projects: From Instant Tagging to News Aggregation

Python Project Practice 1: Instant Tagging

The first project demonstrates a simple markup‑generation tool that later evolves into a flexible, modular system. After refactoring, the program is split into four modules: a handler that outputs fixed HTML tags, a filter module based on regular expressions, a rule module that decides when to apply actions, and a parser that coordinates the workflow.

The handler module provides start and end tags for each markup element and offers a friendly interface for accessing them.

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

The rule module defines condition and action methods; condition checks whether a string matches a rule, and action invokes the handler to output the appropriate tags.

The parser module stores lists of rules and filters, enabling hot‑plugging of new functionality without hard‑coded if…else branches. It iterates over incoming text, applies condition checks, and dispatches actions accordingly.

Python Project Practice 2: Drawing a Nice Picture

This project shows how to generate PDF files using urllib to fetch resources and the reportlab library to create the document. It also illustrates Python’s list comprehension syntax for concise loops.

Sample code (illustrated as an image):

Python Project Practice 3: Universal XML

The third project builds a static website from an XML description. It parses website.xml using Python’s SAX parser (via xml.sax.parse and a custom ContentHandler) to handle start/end element events and character data.

The XML structure contains only page and directory nodes. The program creates HTML files for pages and directories for folder nodes, mirroring the XML hierarchy.

Key implementation snippets are shown as images:

and

The dispatcher function dynamically maps operation names (e.g., startPage, endDirectory) to concrete handlers, falling back to default implementations when a specific handler is missing.

Python Project Practice 4: News Aggregator

The final project aggregates articles from Usenet newsgroups. It defines a NewsAgent that stores sources and destinations, using NNTPSource or SimpleWebSource to fetch data and PlainDestination or HTMLDestination to output it.

The architecture demonstrates layered design: sources retrieve raw content, destinations format and store it, and the agent orchestrates the flow.

Core code illustration: