Using Module Attributes for Code Generation
Explore how to leverage module attributes in Elixir to store and accumulate test case metadata at compile time. Understand the role of the accumulate option in tracking multiple registrations and learn to create macros that generate functions dynamically. This lesson sets the foundation for effective code generation and prepares you for using advanced techniques like before_compile hooks.
We'll cover the following...
Before we can implement the test macro, we need to address a missing piece of our implementation. A user can define multiple test cases, but we have can’t track each test-case definition for inclusion within MathTest.run/0. Fortunately, Elixir solves this use case via module attributes.
Utilizing module attributes
Module attributes allow us to store data in the module at compile time. They are often used in places where constants would be applied in other languages, but Elixir provides other tricks for us to exploit during compilation. We can keep an appended list of registration during the compile phase by taking advantage of the accumulate: true option when registering an attribute. After the module is compiled, ...