Problem Set 5

RSS Feed Filter with Trigger System

A news feed filtering application with a deep OOP inheritance hierarchy implementing strategy and composite design patterns. Includes phrase, time, and logical triggers that compose into complex filter rules, a configuration file parser, and a Tkinter GUI that polls RSS feeds on a background thread.

Implementation

Data Model

NewsStory — data class with guid, title, description, link, and publication date.

Trigger Hierarchy

• Trigger — abstract base class defining the evaluate() interface
• PhraseTrigger(Trigger) — is_phrase_in() normalizes text (replaces punctuation with spaces, lowercases, splits and rejoins) and checks for consecutive word phrase matching
• TitleTrigger(PhraseTrigger) — fires when the title contains the phrase
• DescriptionTrigger(PhraseTrigger) — fires when the description contains the phrase
• TimeTrigger(Trigger) — parses date strings to datetime with EST timezone
• BeforeTrigger(TimeTrigger) / AfterTrigger(TimeTrigger) — fire based on publication date comparison
• NotTrigger(Trigger) — inverts another trigger
• AndTrigger(Trigger) — logical AND of two triggers
• OrTrigger(Trigger) — logical OR of two triggers

Filtering and Configuration

• filter_stories() — filters a list of stories, keeping any story that fires at least one trigger
• read_trigger_config() — parses a trigger configuration file to build trigger objects declaratively

GUI

main_thread() — Tkinter GUI that polls Google/Yahoo RSS feeds every 120 seconds on a background thread and displays filtered stories.