This is a custom DSL compiler plugin for Shopify's Tapioca project that adds missing type information for any class that inherits from T::InexactStruct.
For this data class,
class DataClass < T::InexactStruct
const :a, Integer
const :b, String
const :c, T::Hash[String, String]
const :d, T.untyped
end
running bundle exec tapioca dsl will generate the following .rbi file:
class DataClass
sig do
params(
a: ::Integer,
b: ::String,
c: T::Hash[::String, ::String],
d: T.untyped
).void
end
def initialize(a:, b:, c:, d:,); end
end
For a project that already uses tapioca, no setup is needed beyond adding this gem to your Gemfile.
I like Sorbet's T::Struct and T::InexactStruct classes a lot — if your org has already bought into Sorbet, they make a lot of sense to use as an alternative to Ruby's Struct class.
T::Struct is great, but it comes with the understandble limitation of not being permitted in multi-class inheritance chains — the performance hit of crawling a class' ancestors makes it a poor fit for static type-checking. T::InexactStruct does not come with this limitation, but Sorbet will not typecheck any arguments passed to #new. Tapioca's method of generating RBIs from loaded code make it a very nice tool for shimming in the type-safety that core Sorbet lacks.
Why do I care so much about T::Struct and inheritance? Beyond the obvious (I have T::Struct Foo that is a natural subclass of T::Struct Bar and I want to represent them as such in my code), T::Struct (or T::InexactStruct) has been a useful starting point for data parsing utility classes (API param parsing, API response parsing, etc).