boddhisattva / manage_event_handlers

Manage Event Handlers

About

This is a program to manage events and their handlers. One can find the detailed problem statement here

Code Related Design Decisions

• The key concepts related to the problem domain are EventsManager and Event.

  • An EventManager allows one to subscribe to, unsubscribe from and perform a broadcast in the context of an event
  • An Event basically has a name and a listener as its attributes/properties

• Since an event ideally cannot be complete without an event name and the code/action that gets triggerred as part of an event related broadcast, with this in mind, it is assumed that an Event handler has two main parts - an event name and the block of code that it executes upon being triggerred

  • With this in mind, although it's not explicitly specified in the problem statement, I've added an event name as an additional paramater with regard to subscribe, unsubscribe and broadcast events. With this addition, only if a listener/subscriber, listens to/on a particular event or is capable of responding to it, only then we initiate a listener call as part of a broadcast.

• In order to ensure that each handler will be subscribed at most once, the following things have been accounted for:

  • The subscribers are stored as part of a Set(please see #initialize implementation in EventsManager class) which as a data structure has inherent properties like not allowing duplicates by default.
  • Even if two different Event instances having the same event name and block of code try to be subscribed to at a given point in time, only one of them is stored among the list of subscribers(please see #subscribe implementation in EventsManager class) and the other event instance having the same details doesn't get stored

• Exceptions(including custom ones like DuplicateHandlerError) with appropriate error messages are added at appropriate places to handle edge cases. These are also accompanied with corresponding tests in addition to the tests that cover the happy path.

Usage

Dependencies

• Ruby 3.0
• Please refer to the Gemfile for the other dependencies

Setup

• Run bundle from a project's root directory to install the related dependencies.

Running the tests

• One can run the specs from the project's root directory with the command rspec

Future Scope

• Handling of objects(in addition to blocks).
• Subscribing to multiple event names(that use the same code block) at once