RBS::Siggen

RBS::Siggen generates RBS type signatures by statically analyzing Ruby source code AST with RBS signatures, resolving type information for methods dynamically defined through declarative DSL calls.

Install the gem and add to the application's Gemfile by executing:

bundle add rbs-siggen

If bundler is not being used to manage dependencies, install the gem by executing:

gem install rbs-siggen

Add %a{siggen: ...} annotations with ERB templates to the method definitions whose call sites should generate signatures:

# sig/a.rbs
class A
  %a{siggen:
    def self.<%= name %>: () -> void
  }
  def self.foo: (Symbol name) -> void
end

require "rbs/siggen"

siggen = RBS::Siggen.new
siggen.add_signature(File.read("sig/a.rbs"))
siggen.analyze_ruby(File.read("a.rb"))
puts siggen.generate

Given the following Ruby code:

# a.rb
class A
  foo :bar
  foo :baz
end

Output:

class A
  def self.bar: () -> void

  def self.baz: () -> void
end

Inside the ERB template, method arguments are available by their parameter names as declared in the RBS signature. Keyword arguments and rest keyword arguments are also accessible:

class A
  %a{siggen:
    # baz     = <%= baz %>
    # options = <%= options.to_json %>
    def self.<%= name %>: () -> void
  }
  def self.foo: (Symbol name, baz: bool, **untyped options) -> void
end

Usage: rbs-siggen [options] <lib-path>
    --sig-dir DIR                Path to RBS signature directory (can be specified multiple times)
    --rails                      Preset to generate signatures for Rails applications
    -v, --version                Show version
    -h, --help                   Show this help

Analyze a Ruby file or directory and print the generated RBS to stdout:

rbs-siggen lib/my_dsl.rb

By default, signatures are loaded from the sig/ directory. Use --sig-dir to specify a different directory (repeatable):

rbs-siggen --sig-dir sig --sig-dir other_sig_dir/generated lib/my_dsl.rb

The --rails flag enables a built-in preset for Rails applications. It loads the bundled RBS annotations for ActiveRecord and, when no <lib-path> is given, automatically analyzes db/schema.rb:

rbs-siggen --rails

This generates RBS signatures (e.g. GeneratedAttributeMethods) from the schema definition.

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/kozy4324/rbs-siggen.

The gem is available as open source under the terms of the MIT License.