Convert Downloadable to a module.

Library/Homebrew/api/download.rb

@@ -6,13 +6,20 @@ require "downloadable"
 module Homebrew
   module API
     class DownloadStrategy < CurlDownloadStrategy
+      sig { returns(String) }
+      def name # rubocop:disable Lint/UselessMethodDefinition
+        super
+      end
+
       sig { override.returns(Pathname) }
       def symlink_location
         cache/name
       end
     end
 
-    class Download < Downloadable
+    class Download
+      include Downloadable
+
       sig {
         params(
           url:      String,
@@ -29,6 +36,21 @@ module Homebrew
         @cache = cache
       end
 
+      sig { override.returns(API::DownloadStrategy) }
+      def downloader
+        T.cast(super, API::DownloadStrategy)
+      end
+
+      sig { override.returns(String) }
+      def name
+        downloader.name
+      end
+
+      sig { override.returns(String) }
+      def download_type
+        "API"
+      end
+
       sig { override.returns(Pathname) }
       def cache
         @cache || super
@@ -36,7 +58,7 @@ module Homebrew
 
       sig { returns(Pathname) }
       def symlink_location
-        T.cast(downloader, API::DownloadStrategy).symlink_location
+        downloader.symlink_location
       end
     end
   end

Library/Homebrew/cask/download.rb

@@ -8,7 +8,9 @@ require "cask/quarantine"
 
 module Cask
   # A download corresponding to a {Cask}.
-  class Download < Downloadable
+  class Download
+    include Downloadable
+
     include Context
 
     attr_reader :cask

Library/Homebrew/downloadable.rb

@@ -5,7 +5,7 @@ require "url"
 require "checksum"
 require "download_strategy"
 
-class Downloadable
+module Downloadable
   include Context
   extend T::Helpers
 
@@ -32,7 +32,7 @@ class Downloadable
     @version = @version.dup
   end
 
-  sig { override.returns(T.self_type) }
+  sig { returns(T.self_type) }
   def freeze
     @checksum.freeze
     @mirrors.freeze
@@ -40,14 +40,12 @@ class Downloadable
     super
   end
 
-  sig { returns(String) }
-  def name
-    ""
-  end
+  sig { abstract.returns(String) }
+  def name; end
 
   sig { returns(String) }
   def download_type
-    T.must(T.must(self.class.name).split("::").last).gsub(/([[:lower:]])([[:upper:]])/, '\1 \2').downcase
+    T.must(self.class.name&.split("::")&.last).gsub(/([[:lower:]])([[:upper:]])/, '\1 \2').downcase
   end
 
   sig { returns(T::Boolean) }
@@ -73,16 +71,16 @@ class Downloadable
     version unless version&.null?
   end
 
-  sig { returns(T.class_of(AbstractDownloadStrategy)) }
+  sig { overridable.returns(T.class_of(AbstractDownloadStrategy)) }
   def download_strategy
     @download_strategy ||= determine_url&.download_strategy
   end
 
-  sig { returns(AbstractDownloadStrategy) }
+  sig { overridable.returns(AbstractDownloadStrategy) }
   def downloader
     @downloader ||= begin
       primary_url, *mirrors = determine_url_mirrors
-      raise ArgumentError, "attempted to use a Downloadable without a URL!" if primary_url.blank?
+      raise ArgumentError, "attempted to use a `Downloadable` without a URL!" if primary_url.blank?
 
       download_strategy.new(primary_url, download_name, version,
                             mirrors:, cache:, **T.must(@url).specs)
@@ -90,7 +88,7 @@ class Downloadable
   end
 
   sig {
-    params(
+    overridable.params(
       verify_download_integrity: T::Boolean,
       timeout:                   T.nilable(T.any(Integer, Float)),
       quiet:                     T::Boolean,
@@ -111,7 +109,7 @@ class Downloadable
     download
   end
 
-  sig { params(filename: Pathname).void }
+  sig { overridable.params(filename: Pathname).void }
   def verify_download_integrity(filename)
     if filename.file?
       ohai "Verifying checksum for '#{filename.basename}'" if verbose?

Library/Homebrew/downloadable.rbi

@@ -0,0 +1,5 @@
+# typed: strict
+
+module Downloadable
+  requires_ancestor { Kernel }
+end

Library/Homebrew/resource.rb

@@ -9,7 +9,8 @@ require "extend/on_system"
 # Resource is the fundamental representation of an external resource. The
 # primary formula download, along with other declared resources, are instances
 # of this class.
-class Resource < Downloadable
+class Resource
+  include Downloadable
   include FileUtils
   include OnSystem::MacOSAndLinux
 

Library/Homebrew/retryable_download.rb

@@ -2,7 +2,9 @@
 # frozen_string_literal: true
 
 module Homebrew
-  class RetryableDownload < Downloadable
+  class RetryableDownload
+    include Downloadable
+
     sig { returns(Downloadable) }
     attr_reader :downloadable
     private :downloadable

Library/Homebrew/software_spec.rb

@@ -15,7 +15,9 @@ require "compilers"
 require "macos_version"
 require "extend/on_system"
 
-class SoftwareSpec < Downloadable
+class SoftwareSpec
+  include Downloadable
+
   extend Forwardable
   include OnSystem::MacOSAndLinux
 
@@ -294,7 +296,9 @@ class HeadSoftwareSpec < SoftwareSpec
   end
 end
 
-class Bottle < Downloadable
+class Bottle
+  include Downloadable
+
   class Filename
     attr_reader :name, :version, :tag, :rebuild