Unused yet class verified when inside the module

[developer88]

Hi there.

I was test driving your awesome work and found one edge case:

require 'low_type'
require 'json'
require 'time'
require 'httparty'

module GithubFetcher
  class GithubResponse
    include LowType
    using LowType::Syntax

    type_reader code: Integer, json: Hash

    def initialize(code: Integer , json: Hash )
      @code = code
      @json = json
    end

    def success?() -> { TrueClass | FalseClass }
      (200..299).include?(code)
    end
  end

  class Fetcher
    include LowType
    using LowType::Syntax

    def fetch_response(url =  String | 'https://api.github.com/repos/ruby/ruby/releases/latest') -> { ::GithubFetcher::GithubResponse }
      http = HTTParty.get(url, headers: { 'User-Agent' => 'static-typing-demo' })
      ::GithubFetcher::GithubResponse.new(code: http.code.to_i, json: ::JSON.parse(http.body))
    end

    def fetch(printer = Proc | nil) -> { NilClass | nil }
      resp = fetch_response
      raise "HTTP #{resp.code}" unless resp.success?

      published_at = Time.parse((resp.json['published_at'] || Time.now.utc.iso8601).to_s)
      printer&.call((resp.json['tag_name'] || resp.json['name']).to_s, resp.json['html_url'], published_at)
      nil
    end
  end
end

PRINTER = proc { |tag, url, published_at|
  puts "Fetched tag=#{tag} published_at=#{published_at.utc.iso8601} (url=#{url})"
  nil
}

puts GithubFetcher::Fetcher.new.fetch(PRINTER) if $PROGRAM_NAME == __FILE__

This code generates the following error:

lib/expressions/type_expression.rb:46:in 'LowType::TypeExpression#validate!': Invalid argument type 'NilClass' for parameter 'code'. Valid types: 'Integer' (LowType::ArgumentTypeError)

        raise proxy.error_type, proxy.error_message(value:) if required?

If we move Fetcher and GithubResponse classes out of the module, then the error is gone. Also, even if I do not call the GithubResponse class at all, the error is still there. I use the latest version of the gem 1.1.6 under ruby 4.0.0

[maedi]

One quick first thing, you don't need using LowType::Syntax if you're not using type() method. Also, I don't think it's Ruby 4 related, but I haven't tested LowType with Ruby 4 yet

[maedi]

I thought -> { NilClass | nil } would be equivalent to -> { nil }?

[maedi]

I've also released a new version, I don't think it will fix this issue but it would be nice to confirm it exists there too

[developer88]

I thought -> { NilClass | nil } would be equivalent to -> { nil }?

Yep, that is what I did, but the gem complained about the type. If I do just NilClass it still complains, so the work around is to use both.

[maedi]

Must not be recognising nil as a type expression, the | converts the union types to a type expression automatically but the nil must be missing some processing in that situation

[maedi]

Just an update that I'm currently doing some work on the way we parse modules/classes. So this could help this issue

[maedi]

LowType's file parsing has been completely refactored out into a dedicated gem which has more tests and more capabilities for multi-class and nested module/class files. It's a big improvement... I haven't tested if it fixes your issue yet but just know that LowType has been updated and may (10% chance) fix your issue