[ruby/irb] Standardize command related names

(https://github.com/ruby/irb/pull/873)

* Replace ExtendCommand with Command and standardize command related names

1. Rename lib/irb/extend-command.rb to lib/irb/command.rb
2. Rename lib/irb/cmd/*.rb to lib/irb/command/*.rb
3. Rename test/irb/test_cmd.rb to test/irb/test_command.rb
4. Rename ExtendCommand to Command

* Alias ExtendCommand to Command and deprecate it

* Rename Command::Nop to Command::Base

* Not deprecate old constants just yet

* Add lib/irb/cmd/nop.rb back

https://github.com/ruby/irb/commit/462c1284af

27 files changed, 3 insertions, 1142 deletions

diff --git a/lib/irb/cmd/backtrace.rb b/lib/irb/cmd/backtrace.rb
deleted file mode 100644
index f632894618..0000000000
--- a/lib/irb/cmd/backtrace.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "debug"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class Backtrace < DebugCommand
-      def self.transform_args(args)
-        args&.dump
-      end
-
-      def execute(*args)
-        super(pre_cmds: ["backtrace", *args].join(" "))
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/break.rb b/lib/irb/cmd/break.rb
deleted file mode 100644
index df259a90ca..0000000000
--- a/lib/irb/cmd/break.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "debug"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class Break < DebugCommand
-      def self.transform_args(args)
-        args&.dump
-      end
-
-      def execute(args = nil)
-        super(pre_cmds: "break #{args}")
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/catch.rb b/lib/irb/cmd/catch.rb
deleted file mode 100644
index 40b62c7533..0000000000
--- a/lib/irb/cmd/catch.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "debug"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class Catch < DebugCommand
-      def self.transform_args(args)
-        args&.dump
-      end
-
-      def execute(*args)
-        super(pre_cmds: ["catch", *args].join(" "))
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/chws.rb b/lib/irb/cmd/chws.rb
deleted file mode 100644
index 31045f9bbb..0000000000
--- a/lib/irb/cmd/chws.rb
+++ /dev/null
@@ -1,36 +0,0 @@
-# frozen_string_literal: false
-#
-#   change-ws.rb -
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-
-require_relative "nop"
-require_relative "../ext/change-ws"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-
-    class CurrentWorkingWorkspace < Nop
-      category "Workspace"
-      description "Show the current workspace."
-
-      def execute(*obj)
-        irb_context.main
-      end
-    end
-
-    class ChangeWorkspace < Nop
-      category "Workspace"
-      description "Change the current workspace to an object."
-
-      def execute(*obj)
-        irb_context.change_workspace(*obj)
-        irb_context.main
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/continue.rb b/lib/irb/cmd/continue.rb
deleted file mode 100644
index 9136177eef..0000000000
--- a/lib/irb/cmd/continue.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "debug"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class Continue < DebugCommand
-      def execute(*args)
-        super(do_cmds: ["continue", *args].join(" "))
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/debug.rb b/lib/irb/cmd/debug.rb
deleted file mode 100644
index e236084ca4..0000000000
--- a/lib/irb/cmd/debug.rb
+++ /dev/null
@@ -1,80 +0,0 @@
-require_relative "nop"
-require_relative "../debug"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class Debug < Nop
-      category "Debugging"
-      description "Start the debugger of debug.gem."
-
-      BINDING_IRB_FRAME_REGEXPS = [
-        '<internal:prelude>',
-        binding.method(:irb).source_location.first,
-      ].map { |file| /\A#{Regexp.escape(file)}:\d+:in `irb'\z/ }
-
-      def execute(pre_cmds: nil, do_cmds: nil)
-        if irb_context.with_debugger
-          # If IRB is already running with a debug session, throw the command and IRB.debug_readline will pass it to the debugger.
-          if cmd = pre_cmds || do_cmds
-            throw :IRB_EXIT, cmd
-          else
-            puts "IRB is already running with a debug session."
-            return
-          end
-        else
-          # If IRB is not running with a debug session yet, then:
-          # 1. Check if the debugging command is run from a `binding.irb` call.
-          # 2. If so, try setting up the debug gem.
-          # 3. Insert a debug breakpoint at `Irb#debug_break` with the intended command.
-          # 4. Exit the current Irb#run call via `throw :IRB_EXIT`.
-          # 5. `Irb#debug_break` will be called and trigger the breakpoint, which will run the intended command.
-          unless binding_irb?
-            puts "Debugging commands are only available when IRB is started with binding.irb"
-            return
-          end
-
-          if IRB.respond_to?(:JobManager)
-            warn "Can't start the debugger when IRB is running in a multi-IRB session."
-            return
-          end
-
-          unless IRB::Debug.setup(irb_context.irb)
-            puts <<~MSG
-              You need to install the debug gem before using this command.
-              If you use `bundle exec`, please add `gem "debug"` into your Gemfile.
-            MSG
-            return
-          end
-
-          IRB::Debug.insert_debug_break(pre_cmds: pre_cmds, do_cmds: do_cmds)
-
-          # exit current Irb#run call
-          throw :IRB_EXIT
-        end
-      end
-
-      private
-
-      def binding_irb?
-        caller.any? do |frame|
-          BINDING_IRB_FRAME_REGEXPS.any? do |regexp|
-            frame.match?(regexp)
-          end
-        end
-      end
-    end
-
-    class DebugCommand < Debug
-      def self.category
-        "Debugging"
-      end
-
-      def self.description
-        command_name = self.name.split("::").last.downcase
-        "Start the debugger of debug.gem and run its `#{command_name}` command."
-      end
-    end
-  end
-end
diff --git a/lib/irb/cmd/delete.rb b/lib/irb/cmd/delete.rb
deleted file mode 100644
index aeb26d2572..0000000000
--- a/lib/irb/cmd/delete.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "debug"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class Delete < DebugCommand
-      def execute(*args)
-        super(pre_cmds: ["delete", *args].join(" "))
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/edit.rb b/lib/irb/cmd/edit.rb
deleted file mode 100644
index dae65f3c39..0000000000
--- a/lib/irb/cmd/edit.rb
+++ /dev/null
@@ -1,54 +0,0 @@
-require 'shellwords'
-require_relative "nop"
-require_relative "../source_finder"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class Edit < Nop
-      category "Misc"
-      description 'Open a file with the editor command defined with `ENV["VISUAL"]` or `ENV["EDITOR"]`.'
-
-      class << self
-        def transform_args(args)
-          # Return a string literal as is for backward compatibility
-          if args.nil? || args.empty? || string_literal?(args)
-            args
-          else # Otherwise, consider the input as a String for convenience
-            args.strip.dump
-          end
-        end
-      end
-
-      def execute(*args)
-        path = args.first
-
-        if path.nil?
-          path = @irb_context.irb_path
-        elsif !File.exist?(path)
-          source = SourceFinder.new(@irb_context).find_source(path)
-
-          if source&.file_exist? && !source.binary_file?
-            path = source.file
-          end
-        end
-
-        unless File.exist?(path)
-          puts "Can not find file: #{path}"
-          return
-        end
-
-        if editor = (ENV['VISUAL'] || ENV['EDITOR'])
-          puts "command: '#{editor}'"
-          puts "   path: #{path}"
-          system(*Shellwords.split(editor), path)
-        else
-          puts "Can not find editor setting: ENV['VISUAL'] or ENV['EDITOR']"
-        end
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/exit.rb b/lib/irb/cmd/exit.rb
deleted file mode 100644
index 415e555335..0000000000
--- a/lib/irb/cmd/exit.rb
+++ /dev/null
@@ -1,22 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "nop"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class Exit < Nop
-      category "IRB"
-      description "Exit the current irb session."
-
-      def execute(*)
-        IRB.irb_exit
-      rescue UncaughtThrowError
-        Kernel.exit
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/finish.rb b/lib/irb/cmd/finish.rb
deleted file mode 100644
index 29f100feb5..0000000000
--- a/lib/irb/cmd/finish.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "debug"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class Finish < DebugCommand
-      def execute(*args)
-        super(do_cmds: ["finish", *args].join(" "))
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/force_exit.rb b/lib/irb/cmd/force_exit.rb
deleted file mode 100644
index 7e9b308de0..0000000000
--- a/lib/irb/cmd/force_exit.rb
+++ /dev/null
@@ -1,22 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "nop"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class ForceExit < Nop
-      category "IRB"
-      description "Exit the current process."
-
-      def execute(*)
-        throw :IRB_EXIT, true
-      rescue UncaughtThrowError
-        Kernel.exit!
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/help.rb b/lib/irb/cmd/help.rb
deleted file mode 100644
index 7f894688cc..0000000000
--- a/lib/irb/cmd/help.rb
+++ /dev/null
@@ -1,12 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "show_cmds"
-
-module IRB
-  module ExtendCommand
-    class Help < ShowCmds
-      category "IRB"
-      description "List all available commands and their description."
-    end
-  end
-end
diff --git a/lib/irb/cmd/history.rb b/lib/irb/cmd/history.rb
deleted file mode 100644
index 5b712fa44d..0000000000
--- a/lib/irb/cmd/history.rb
+++ /dev/null
@@ -1,47 +0,0 @@
-# frozen_string_literal: true
-
-require "stringio"
-require_relative "nop"
-require_relative "../pager"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class History < Nop
-      category "IRB"
-      description "Shows the input history. `-g [query]` or `-G [query]` allows you to filter the output."
-
-      def self.transform_args(args)
-        match = args&.match(/(-g|-G)\s+(?<grep>.+)\s*\n\z/)
-        return unless match
-
-        "grep: #{Regexp.new(match[:grep]).inspect}"
-      end
-
-      def execute(grep: nil)
-        formatted_inputs = irb_context.io.class::HISTORY.each_with_index.reverse_each.filter_map do |input, index|
-          next if grep && !input.match?(grep)
-
-          header = "#{index}: "
-
-          first_line, *other_lines = input.split("\n")
-          first_line = "#{header}#{first_line}"
-
-          truncated_lines = other_lines.slice!(1..) # Show 1 additional line (2 total)
-          other_lines << "..." if truncated_lines&.any?
-
-          other_lines.map! do |line|
-            " " * header.length + line
-          end
-
-          [first_line, *other_lines].join("\n") + "\n"
-        end
-
-        Pager.page_content(formatted_inputs.join)
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/info.rb b/lib/irb/cmd/info.rb
deleted file mode 100644
index 2c0a32b34f..0000000000
--- a/lib/irb/cmd/info.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "debug"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class Info < DebugCommand
-      def self.transform_args(args)
-        args&.dump
-      end
-
-      def execute(*args)
-        super(pre_cmds: ["info", *args].join(" "))
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/irb_info.rb b/lib/irb/cmd/irb_info.rb
deleted file mode 100644
index 5b905a09bd..0000000000
--- a/lib/irb/cmd/irb_info.rb
+++ /dev/null
@@ -1,34 +0,0 @@
-# frozen_string_literal: false
-
-require_relative "nop"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class IrbInfo < Nop
-      category "IRB"
-      description "Show information about IRB."
-
-      def execute
-        str  = "Ruby version: #{RUBY_VERSION}\n"
-        str += "IRB version: #{IRB.version}\n"
-        str += "InputMethod: #{IRB.CurrentContext.io.inspect}\n"
-        str += "Completion: #{IRB.CurrentContext.io.respond_to?(:completion_info) ? IRB.CurrentContext.io.completion_info : 'off'}\n"
-        str += ".irbrc path: #{IRB.rc_file}\n" if File.exist?(IRB.rc_file)
-        str += "RUBY_PLATFORM: #{RUBY_PLATFORM}\n"
-        str += "LANG env: #{ENV["LANG"]}\n" if ENV["LANG"] && !ENV["LANG"].empty?
-        str += "LC_ALL env: #{ENV["LC_ALL"]}\n" if ENV["LC_ALL"] && !ENV["LC_ALL"].empty?
-        str += "East Asian Ambiguous Width: #{Reline.ambiguous_width.inspect}\n"
-        if RbConfig::CONFIG['host_os'] =~ /mswin|msys|mingw|cygwin|bccwin|wince|emc/
-          codepage = `chcp`.b.sub(/.*: (\d+)\n/, '\1')
-          str += "Code page: #{codepage}\n"
-        end
-        puts str
-        nil
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/load.rb b/lib/irb/cmd/load.rb
deleted file mode 100644
index a3e797a7e0..0000000000
--- a/lib/irb/cmd/load.rb
+++ /dev/null
@@ -1,76 +0,0 @@
-# frozen_string_literal: false
-#
-#   load.rb -
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-
-require_relative "nop"
-require_relative "../ext/loader"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class LoaderCommand < Nop
-      include IrbLoader
-
-      def raise_cmd_argument_error
-        raise CommandArgumentError.new("Please specify the file name.")
-      end
-    end
-
-    class Load < LoaderCommand
-      category "IRB"
-      description "Load a Ruby file."
-
-      def execute(file_name = nil, priv = nil)
-        raise_cmd_argument_error unless file_name
-        irb_load(file_name, priv)
-      end
-    end
-
-    class Require < LoaderCommand
-      category "IRB"
-      description "Require a Ruby file."
-      def execute(file_name = nil)
-        raise_cmd_argument_error unless file_name
-
-        rex = Regexp.new("#{Regexp.quote(file_name)}(\.o|\.rb)?")
-        return false if $".find{|f| f =~ rex}
-
-        case file_name
-        when /\.rb$/
-          begin
-            if irb_load(file_name)
-              $".push file_name
-              return true
-            end
-          rescue LoadError
-          end
-        when /\.(so|o|sl)$/
-          return ruby_require(file_name)
-        end
-
-        begin
-          irb_load(f = file_name + ".rb")
-          $".push f
-          return true
-        rescue LoadError
-          return ruby_require(file_name)
-        end
-      end
-    end
-
-    class Source < LoaderCommand
-      category "IRB"
-      description "Loads a given file in the current session."
-
-      def execute(file_name = nil)
-        raise_cmd_argument_error unless file_name
-
-        source_file(file_name)
-      end
-    end
-  end
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/ls.rb b/lib/irb/cmd/ls.rb
deleted file mode 100644
index 791b1c1b21..0000000000
--- a/lib/irb/cmd/ls.rb
+++ /dev/null
@@ -1,139 +0,0 @@
-# frozen_string_literal: true
-
-require "reline"
-require "stringio"
-require_relative "nop"
-require_relative "../pager"
-require_relative "../color"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class Ls < Nop
-      category "Context"
-      description "Show methods, constants, and variables. `-g [query]` or `-G [query]` allows you to filter out the output."
-
-      def self.transform_args(args)
-        if match = args&.match(/\A(?<args>.+\s|)(-g|-G)\s+(?<grep>[^\s]+)\s*\n\z/)
-          args = match[:args]
-          "#{args}#{',' unless args.chomp.empty?} grep: /#{match[:grep]}/"
-        else
-          args
-        end
-      end
-
-      def execute(*arg, grep: nil)
-        o = Output.new(grep: grep)
-
-        obj    = arg.empty? ? irb_context.workspace.main : arg.first
-        locals = arg.empty? ? irb_context.workspace.binding.local_variables : []
-        klass  = (obj.class == Class || obj.class == Module ? obj : obj.class)
-
-        o.dump("constants", obj.constants) if obj.respond_to?(:constants)
-        dump_methods(o, klass, obj)
-        o.dump("instance variables", obj.instance_variables)
-        o.dump("class variables", klass.class_variables)
-        o.dump("locals", locals)
-        o.print_result
-      end
-
-      def dump_methods(o, klass, obj)
-        singleton_class = begin obj.singleton_class; rescue TypeError; nil end
-        dumped_mods = Array.new
-        ancestors = klass.ancestors
-        ancestors = ancestors.reject { |c| c >= Object } if klass < Object
-        singleton_ancestors = (singleton_class&.ancestors || []).reject { |c| c >= Class }
-
-        # singleton_class' ancestors should be at the front
-        maps = class_method_map(singleton_ancestors, dumped_mods) + class_method_map(ancestors, dumped_mods)
-        maps.each do |mod, methods|
-          name = mod == singleton_class ? "#{klass}.methods" : "#{mod}#methods"
-          o.dump(name, methods)
-        end
-      end
-
-      def class_method_map(classes, dumped_mods)
-        dumped_methods = Array.new
-        classes.map do |mod|
-          next if dumped_mods.include? mod
-
-          dumped_mods << mod
-
-          methods = mod.public_instance_methods(false).select do |method|
-            if dumped_methods.include? method
-              false
-            else
-              dumped_methods << method
-              true
-            end
-          end
-
-          [mod, methods]
-        end.compact
-      end
-
-      class Output
-        MARGIN = "  "
-
-        def initialize(grep: nil)
-          @grep = grep
-          @line_width = screen_width - MARGIN.length # right padding
-          @io = StringIO.new
-        end
-
-        def print_result
-          Pager.page_content(@io.string)
-        end
-
-        def dump(name, strs)
-          strs = strs.grep(@grep) if @grep
-          strs = strs.sort
-          return if strs.empty?
-
-          # Attempt a single line
-          @io.print "#{Color.colorize(name, [:BOLD, :BLUE])}: "
-          if fits_on_line?(strs, cols: strs.size, offset: "#{name}: ".length)
-            @io.puts strs.join(MARGIN)
-            return
-          end
-          @io.puts
-
-          # Dump with the largest # of columns that fits on a line
-          cols = strs.size
-          until fits_on_line?(strs, cols: cols, offset: MARGIN.length) || cols == 1
-            cols -= 1
-          end
-          widths = col_widths(strs, cols: cols)
-          strs.each_slice(cols) do |ss|
-            @io.puts ss.map.with_index { |s, i| "#{MARGIN}%-#{widths[i]}s" % s }.join
-          end
-        end
-
-        private
-
-        def fits_on_line?(strs, cols:, offset: 0)
-          width = col_widths(strs, cols: cols).sum + MARGIN.length * (cols - 1)
-          width <= @line_width - offset
-        end
-
-        def col_widths(strs, cols:)
-          cols.times.map do |col|
-            (col...strs.size).step(cols).map do |i|
-              strs[i].length
-            end.max
-          end
-        end
-
-        def screen_width
-          Reline.get_screen_size.last
-        rescue Errno::EINVAL # in `winsize': Invalid argument - <STDIN>
-          80
-        end
-      end
-      private_constant :Output
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/measure.rb b/lib/irb/cmd/measure.rb
deleted file mode 100644
index 4e1125a0a6..0000000000
--- a/lib/irb/cmd/measure.rb
+++ /dev/null
@@ -1,45 +0,0 @@
-require_relative "nop"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class Measure < Nop
-      category "Misc"
-      description "`measure` enables the mode to measure processing time. `measure :off` disables it."
-
-      def initialize(*args)
-        super(*args)
-      end
-
-      def execute(type = nil, arg = nil)
-        # Please check IRB.init_config in lib/irb/init.rb that sets
-        # IRB.conf[:MEASURE_PROC] to register default "measure" methods,
-        # "measure :time" (abbreviated as "measure") and "measure :stackprof".
-
-        if block_given?
-          warn 'Configure IRB.conf[:MEASURE_PROC] to add custom measure methods.'
-          return
-        end
-
-        case type
-        when :off
-          IRB.unset_measure_callback(arg)
-        when :list
-          IRB.conf[:MEASURE_CALLBACKS].each do |type_name, _, arg_val|
-            puts "- #{type_name}" + (arg_val ? "(#{arg_val.inspect})" : '')
-          end
-        when :on
-          added = IRB.set_measure_callback(arg)
-          puts "#{added[0]} is added." if added
-        else
-          added = IRB.set_measure_callback(type, arg)
-          puts "#{added[0]} is added." if added
-        end
-        nil
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/next.rb b/lib/irb/cmd/next.rb
deleted file mode 100644
index d29c82e7fc..0000000000
--- a/lib/irb/cmd/next.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "debug"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class Next < DebugCommand
-      def execute(*args)
-        super(do_cmds: ["next", *args].join(" "))
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/nop.rb b/lib/irb/cmd/nop.rb
index 7fb197c51f..49f89bac95 100644
--- a/lib/irb/cmd/nop.rb
+++ b/lib/irb/cmd/nop.rb
@@ -1,53 +1,4 @@
-# frozen_string_literal: false
-#
-#   nop.rb -
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
+# frozen_string_literal: true
 
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class CommandArgumentError < StandardError; end
-
-    class Nop
-      class << self
-        def category(category = nil)
-          @category = category if category
-          @category
-        end
-
-        def description(description = nil)
-          @description = description if description
-          @description
-        end
-
-        private
-
-        def string_literal?(args)
-          sexp = Ripper.sexp(args)
-          sexp && sexp.size == 2 && sexp.last&.first&.first == :string_literal
-        end
-      end
-
-      def self.execute(irb_context, *opts, **kwargs, &block)
-        command = new(irb_context)
-        command.execute(*opts, **kwargs, &block)
-      rescue CommandArgumentError => e
-        puts e.message
-      end
-
-      def initialize(irb_context)
-        @irb_context = irb_context
-      end
-
-      attr_reader :irb_context
-
-      def execute(*opts)
-        #nop
-      end
-    end
-  end
-
-  # :startdoc:
-end
+# This file is just a placeholder for backward-compatibility.
+# Please require 'irb' and inheirt your command from `IRB::Command::Base` instead.
diff --git a/lib/irb/cmd/pushws.rb b/lib/irb/cmd/pushws.rb
deleted file mode 100644
index 59996ceb0c..0000000000
--- a/lib/irb/cmd/pushws.rb
+++ /dev/null
@@ -1,45 +0,0 @@
-# frozen_string_literal: false
-#
-#   change-ws.rb -
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-
-require_relative "nop"
-require_relative "../ext/workspaces"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class Workspaces < Nop
-      category "Workspace"
-      description "Show workspaces."
-
-      def execute(*obj)
-        irb_context.workspaces.collect{|ws| ws.main}
-      end
-    end
-
-    class PushWorkspace < Workspaces
-      category "Workspace"
-      description "Push an object to the workspace stack."
-
-      def execute(*obj)
-        irb_context.push_workspace(*obj)
-        super
-      end
-    end
-
-    class PopWorkspace < Workspaces
-      category "Workspace"
-      description "Pop a workspace from the workspace stack."
-
-      def execute(*obj)
-        irb_context.pop_workspace(*obj)
-        super
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/show_cmds.rb b/lib/irb/cmd/show_cmds.rb
deleted file mode 100644
index a8d899e4ac..0000000000
--- a/lib/irb/cmd/show_cmds.rb
+++ /dev/null
@@ -1,59 +0,0 @@
-# frozen_string_literal: true
-
-require "stringio"
-require_relative "nop"
-require_relative "../pager"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class ShowCmds < Nop
-      category "IRB"
-      description "List all available commands and their description."
-
-      def execute(*args)
-        commands_info = IRB::ExtendCommandBundle.all_commands_info
-        commands_grouped_by_categories = commands_info.group_by { |cmd| cmd[:category] }
-
-        user_aliases = irb_context.instance_variable_get(:@user_aliases)
-
-        commands_grouped_by_categories["Aliases"] = user_aliases.map do |alias_name, target|
-          { display_name: alias_name, description: "Alias for `#{target}`" }
-        end
-
-        if irb_context.with_debugger
-          # Remove the original "Debugging" category
-          commands_grouped_by_categories.delete("Debugging")
-          # Remove the `help` command as it's delegated to the debugger
-          commands_grouped_by_categories["Context"].delete_if { |cmd| cmd[:display_name] == :help }
-          # Add an empty "Debugging (from debug.gem)" category at the end
-          commands_grouped_by_categories["Debugging (from debug.gem)"] = []
-        end
-
-        longest_cmd_name_length = commands_info.map { |c| c[:display_name].length }.max
-
-        output = StringIO.new
-
-        commands_grouped_by_categories.each do |category, cmds|
-          output.puts Color.colorize(category, [:BOLD])
-
-          cmds.each do |cmd|
-            output.puts "  #{cmd[:display_name].to_s.ljust(longest_cmd_name_length)}    #{cmd[:description]}"
-          end
-
-          output.puts
-        end
-
-        # Append the debugger help at the end
-        if irb_context.with_debugger
-          output.puts DEBUGGER__.help
-        end
-
-        Pager.page_content(output.string)
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/show_doc.rb b/lib/irb/cmd/show_doc.rb
deleted file mode 100644
index 99dd9ab95a..0000000000
--- a/lib/irb/cmd/show_doc.rb
+++ /dev/null
@@ -1,48 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "nop"
-
-module IRB
-  module ExtendCommand
-    class ShowDoc < Nop
-      class << self
-        def transform_args(args)
-          # Return a string literal as is for backward compatibility
-          if args.empty? || string_literal?(args)
-            args
-          else # Otherwise, consider the input as a String for convenience
-            args.strip.dump
-          end
-        end
-      end
-
-      category "Context"
-      description "Enter the mode to look up RI documents."
-
-      def execute(*names)
-        require 'rdoc/ri/driver'
-
-        unless ShowDoc.const_defined?(:Ri)
-          opts = RDoc::RI::Driver.process_args([])
-          ShowDoc.const_set(:Ri, RDoc::RI::Driver.new(opts))
-        end
-
-        if names.empty?
-          Ri.interactive
-        else
-          names.each do |name|
-            begin
-              Ri.display_name(name.to_s)
-            rescue RDoc::RI::Error
-              puts $!.message
-            end
-          end
-        end
-
-        nil
-      rescue LoadError, SystemExit
-        warn "Can't display document because `rdoc` is not installed."
-      end
-    end
-  end
-end
diff --git a/lib/irb/cmd/show_source.rb b/lib/irb/cmd/show_source.rb
deleted file mode 100644
index cd07de3e90..0000000000
--- a/lib/irb/cmd/show_source.rb
+++ /dev/null
@@ -1,68 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "nop"
-require_relative "../source_finder"
-require_relative "../pager"
-require_relative "../color"
-
-module IRB
-  module ExtendCommand
-    class ShowSource < Nop
-      category "Context"
-      description "Show the source code of a given method or constant."
-
-      class << self
-        def transform_args(args)
-          # Return a string literal as is for backward compatibility
-          if args.empty? || string_literal?(args)
-            args
-          else # Otherwise, consider the input as a String for convenience
-            args.strip.dump
-          end
-        end
-      end
-
-      def execute(str = nil)
-        unless str.is_a?(String)
-          puts "Error: Expected a string but got #{str.inspect}"
-          return
-        end
-
-        str, esses = str.split(" -")
-        super_level = esses ? esses.count("s") : 0
-        source = SourceFinder.new(@irb_context).find_source(str, super_level)
-
-        if source
-          show_source(source)
-        elsif super_level > 0
-          puts "Error: Couldn't locate a super definition for #{str}"
-        else
-          puts "Error: Couldn't locate a definition for #{str}"
-        end
-        nil
-      end
-
-      private
-
-      def show_source(source)
-        if source.binary_file?
-          content = "\n#{bold('Defined in binary file')}: #{source.file}\n\n"
-        else
-          code = source.colorized_content || 'Source not available'
-          content = <<~CONTENT
-
-            #{bold("From")}: #{source.file}:#{source.line}
-
-            #{code.chomp}
-
-          CONTENT
-        end
-        Pager.page_content(content)
-      end
-
-      def bold(str)
-        Color.colorize(str, [:BOLD])
-      end
-    end
-  end
-end
diff --git a/lib/irb/cmd/step.rb b/lib/irb/cmd/step.rb
deleted file mode 100644
index 2bc74a9d79..0000000000
--- a/lib/irb/cmd/step.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "debug"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class Step < DebugCommand
-      def execute(*args)
-        super(do_cmds: ["step", *args].join(" "))
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/subirb.rb b/lib/irb/cmd/subirb.rb
deleted file mode 100644
index 5ffd646416..0000000000
--- a/lib/irb/cmd/subirb.rb
+++ /dev/null
@@ -1,109 +0,0 @@
-# frozen_string_literal: false
-#
-#   multi.rb -
-#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
-#
-
-require_relative "nop"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class MultiIRBCommand < Nop
-      def execute(*args)
-        extend_irb_context
-      end
-
-      private
-
-      def print_deprecated_warning
-        warn <<~MSG
-          Multi-irb commands are deprecated and will be removed in IRB 2.0.0. Please use workspace commands instead.
-          If you have any use case for multi-irb, please leave a comment at https://github.com/ruby/irb/issues/653
-        MSG
-      end
-
-      def extend_irb_context
-        # this extension patches IRB context like IRB.CurrentContext
-        require_relative "../ext/multi-irb"
-      end
-
-      def print_debugger_warning
-        warn "Multi-IRB commands are not available when the debugger is enabled."
-      end
-    end
-
-    class IrbCommand < MultiIRBCommand
-      category "Multi-irb (DEPRECATED)"
-      description "Start a child IRB."
-
-      def execute(*obj)
-        print_deprecated_warning
-
-        if irb_context.with_debugger
-          print_debugger_warning
-          return
-        end
-
-        super
-        IRB.irb(nil, *obj)
-      end
-    end
-
-    class Jobs < MultiIRBCommand
-      category "Multi-irb (DEPRECATED)"
-      description "List of current sessions."
-
-      def execute
-        print_deprecated_warning
-
-        if irb_context.with_debugger
-          print_debugger_warning
-          return
-        end
-
-        super
-        IRB.JobManager
-      end
-    end
-
-    class Foreground < MultiIRBCommand
-      category "Multi-irb (DEPRECATED)"
-      description "Switches to the session of the given number."
-
-      def execute(key = nil)
-        print_deprecated_warning
-
-        if irb_context.with_debugger
-          print_debugger_warning
-          return
-        end
-
-        super
-
-        raise CommandArgumentError.new("Please specify the id of target IRB job (listed in the `jobs` command).") unless key
-        IRB.JobManager.switch(key)
-      end
-    end
-
-    class Kill < MultiIRBCommand
-      category "Multi-irb (DEPRECATED)"
-      description "Kills the session with the given number."
-
-      def execute(*keys)
-        print_deprecated_warning
-
-        if irb_context.with_debugger
-          print_debugger_warning
-          return
-        end
-
-        super
-        IRB.JobManager.kill(*keys)
-      end
-    end
-  end
-
-  # :startdoc:
-end
diff --git a/lib/irb/cmd/whereami.rb b/lib/irb/cmd/whereami.rb
deleted file mode 100644
index 8f56ba073d..0000000000
--- a/lib/irb/cmd/whereami.rb
+++ /dev/null
@@ -1,25 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "nop"
-
-module IRB
-  # :stopdoc:
-
-  module ExtendCommand
-    class Whereami < Nop
-      category "Context"
-      description "Show the source code around binding.irb again."
-
-      def execute(*)
-        code = irb_context.workspace.code_around_binding
-        if code
-          puts code
-        else
-          puts "The current context doesn't have code."
-        end
-      end
-    end
-  end
-
-  # :startdoc:
-end