Prefer class << self over def self.method

Author: amatsuda

app/models/message.rb

@@ -10,38 +10,40 @@ class Message < ApplicationRecord
   # https://blade.ruby-lang.org/ruby-talk/410000 is not.
   self.skip_time_zone_conversion_for_attributes = [:published_at]
 
-  def self.from_s3(list_name, list_seq, s3_client = Aws::S3::Client.new(region: BLADE_BUCKET_REGION))
-    obj = s3_client.get_object(bucket: BLADE_BUCKET_NAME, key: "#{list_name}/#{list_seq}")
-
-    m = self.from_string(obj.body.read)
-    m.list_id = List.find_by_name(list_name).id
-    m.list_seq = list_seq
-    m
-  end
-
-  def self.from_string(str)
-    # There are a few hacks to import messages from blade.ruby-lang.org's
-    # S3 bucket.
-
-    # Need to call String#b. There are messages that have headers in non-UTF8,
-    # but the body is in UTF-8, such as ruby-list:2882.
-    headers_str, body = str.b.split(/\n\n/, 2)
-
-    # ruby-list:2840 doesn't have a proper From header.
-    headers_str = Kconv.toutf8(headers_str).gsub(/\r\n/, '')
-
-    headers = headers_str.split(/\n/).map { |line|
-      line.split(/:\s+/, 2)
-    }.to_h
-
-    published_at = DateTime.strptime(headers['Date'], '%Y-%m-%dT%H:%M:%S%:z')
-
-    self.new(
-      body: Kconv.toutf8(body),
-      subject: headers['Subject'],
-      from: headers['From'],
-      published_at: published_at,
-    )
+  class << self
+    def from_s3(list_name, list_seq, s3_client = Aws::S3::Client.new(region: BLADE_BUCKET_REGION))
+      obj = s3_client.get_object(bucket: BLADE_BUCKET_NAME, key: "#{list_name}/#{list_seq}")
+
+      m = self.from_string(obj.body.read)
+      m.list_id = List.find_by_name(list_name).id
+      m.list_seq = list_seq
+      m
+    end
+
+    def from_string(str)
+      # There are a few hacks to import messages from blade.ruby-lang.org's
+      # S3 bucket.
+
+      # Need to call String#b. There are messages that have headers in non-UTF8,
+      # but the body is in UTF-8, such as ruby-list:2882.
+      headers_str, body = str.b.split(/\n\n/, 2)
+
+      # ruby-list:2840 doesn't have a proper From header.
+      headers_str = Kconv.toutf8(headers_str).gsub(/\r\n/, '')
+
+      headers = headers_str.split(/\n/).map { |line|
+        line.split(/:\s+/, 2)
+      }.to_h
+
+      published_at = DateTime.strptime(headers['Date'], '%Y-%m-%dT%H:%M:%S%:z')
+
+      self.new(
+        body: Kconv.toutf8(body),
+        subject: headers['Subject'],
+        from: headers['From'],
+        published_at: published_at,
+      )
+    end
   end
 
   def reload_from_s3(s3_client = Aws::S3::Client.new(region: BLADE_BUCKET_REGION))