How to Create and Use Custom Exceptions in Elixir

The article begins by defining what an exception is, using a StackOverflow definition: an exception is thrown when a fundamental assumption of the current code block is found to be false. Examples include network failures or database issues. It then delves into the anatomy of Elixir's exceptions, demonstrating that they are structs with fields that can be inspected and manipulated. The article then discusses when and why one should use custom exceptions, such as in library creation or for specific application errors that warrant them. A detailed instruction set is provided on how to create custom exceptions using the 'defexception' macro and how to use them effectively in Elixir code. The article goes on to explain how to handle repackaging existing exceptions or converting exits (like timeouts) into exceptions for better error tracking and management. Throughout, the article aims to provide insights on making debugging and error tracking easier in Elixir applications.