[ruby/irb] Remove useless begin/end [ci skip]

(https://github.com/ruby/irb/pull/680)

The `rescue` was removed at https://github.com/ruby/irb/commit/420e7d227011.

https://github.com/ruby/irb/commit/8fa688e9c0

lib/irb/input-method.rb

@@ -159,66 +159,64 @@ module IRB
     end
   end
 
-  begin
+  class ReadlineInputMethod < StdioInputMethod
-    class ReadlineInputMethod < StdioInputMethod
+    def self.initialize_readline
-      def self.initialize_readline
+      require "readline"
-        require "readline"
+    rescue LoadError
-      rescue LoadError
+    else
+      include ::Readline
+    end
+
+    include HistorySavingAbility
+
+    # Creates a new input method object using Readline
+    def initialize
+      self.class.initialize_readline
+      if Readline.respond_to?(:encoding_system_needs)
+        IRB.__send__(:set_encoding, Readline.encoding_system_needs.name, override: false)
+      end
+
+      super
+
+      @eof = false
+
+      if Readline.respond_to?("basic_word_break_characters=")
+        Readline.basic_word_break_characters = IRB::InputCompletor::BASIC_WORD_BREAK_CHARACTERS
+      end
+      Readline.completion_append_character = nil
+      Readline.completion_proc = IRB::InputCompletor::CompletionProc
+    end
+
+    # Reads the next line from this input method.
+    #
+    # See IO#gets for more information.
+    def gets
+      Readline.input = @stdin
+      Readline.output = @stdout
+      if l = readline(@prompt, false)
+        HISTORY.push(l) if !l.empty?
+        @line[@line_no += 1] = l + "\n"
       else
-        include ::Readline
+        @eof = true
+        l
       end
+    end
 
-      include HistorySavingAbility
+    # Whether the end of this input method has been reached, returns +true+
+    # if there is no more data to read.
+    #
+    # See IO#eof? for more information.
+    def eof?
+      @eof
+    end
 
-      # Creates a new input method object using Readline
+    # For debug message
-      def initialize
+    def inspect
-        self.class.initialize_readline
+      readline_impl = (defined?(Reline) && Readline == Reline) ? 'Reline' : 'ext/readline'
-        if Readline.respond_to?(:encoding_system_needs)
+      str = "ReadlineInputMethod with #{readline_impl} #{Readline::VERSION}"
-          IRB.__send__(:set_encoding, Readline.encoding_system_needs.name, override: false)
+      inputrc_path = File.expand_path(ENV['INPUTRC'] || '~/.inputrc')
-        end
+      str += " and #{inputrc_path}" if File.exist?(inputrc_path)
-
+      str
-        super
-
-        @eof = false
-
-        if Readline.respond_to?("basic_word_break_characters=")
-          Readline.basic_word_break_characters = IRB::InputCompletor::BASIC_WORD_BREAK_CHARACTERS
-        end
-        Readline.completion_append_character = nil
-        Readline.completion_proc = IRB::InputCompletor::CompletionProc
-      end
-
-      # Reads the next line from this input method.
-      #
-      # See IO#gets for more information.
-      def gets
-        Readline.input = @stdin
-        Readline.output = @stdout
-        if l = readline(@prompt, false)
-          HISTORY.push(l) if !l.empty?
-          @line[@line_no += 1] = l + "\n"
-        else
-          @eof = true
-          l
-        end
-      end
-
-      # Whether the end of this input method has been reached, returns +true+
-      # if there is no more data to read.
-      #
-      # See IO#eof? for more information.
-      def eof?
-        @eof
-      end
-
-      # For debug message
-      def inspect
-        readline_impl = (defined?(Reline) && Readline == Reline) ? 'Reline' : 'ext/readline'
-        str = "ReadlineInputMethod with #{readline_impl} #{Readline::VERSION}"
-        inputrc_path = File.expand_path(ENV['INPUTRC'] || '~/.inputrc')
-        str += " and #{inputrc_path}" if File.exist?(inputrc_path)
-        str
-      end
     end
   end