Add "show_cmds" command to list all commands' descriptions (#463)

Author: st0012

lib/irb/cmd/backtrace.rb

@@ -6,7 +6,7 @@ module IRB
   # :stopdoc:
 
   module ExtendCommand
-    class Backtrace < Debug
+    class Backtrace < DebugCommand
       def self.transform_args(args)
         args&.dump
       end

lib/irb/cmd/break.rb

@@ -6,7 +6,7 @@ module IRB
   # :stopdoc:
 
   module ExtendCommand
-    class Break < Debug
+    class Break < DebugCommand
       def self.transform_args(args)
         args&.dump
       end

lib/irb/cmd/catch.rb

@@ -6,7 +6,7 @@ module IRB
   # :stopdoc:
 
   module ExtendCommand
-    class Catch < Debug
+    class Catch < DebugCommand
       def self.transform_args(args)
         args&.dump
       end

lib/irb/cmd/chws.rb

@@ -19,12 +19,18 @@ module IRB
   module ExtendCommand
 
     class CurrentWorkingWorkspace < Nop
+      category "IRB"
+      description "Show the current workspace."
+
       def execute(*obj)
         irb_context.main
       end
     end
 
     class ChangeWorkspace < Nop
+      category "IRB"
+      description "Change the current workspace to an object."
+
       def execute(*obj)
         irb_context.change_workspace(*obj)
         irb_context.main

lib/irb/cmd/continue.rb

@@ -6,7 +6,7 @@ module IRB
   # :stopdoc:
 
   module ExtendCommand
-    class Continue < Debug
+    class Continue < DebugCommand
       def execute(*args)
         super(do_cmds: ["continue", *args].join(" "))
       end

lib/irb/cmd/debug.rb

@@ -5,6 +5,9 @@ module IRB
 
   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,
@@ -108,5 +111,16 @@ def load_bundled_debug_gem
         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

lib/irb/cmd/delete.rb

@@ -6,7 +6,7 @@ module IRB
   # :stopdoc:
 
   module ExtendCommand
-    class Delete < Debug
+    class Delete < DebugCommand
       def execute(*args)
         super(pre_cmds: ["delete", *args].join(" "))
       end

lib/irb/cmd/edit.rb

@@ -6,6 +6,9 @@ module IRB
 
   module ExtendCommand
     class Edit < Nop
+      category "Misc"
+      description 'Open a file with the editor command defined with `ENV["EDITOR"]`.'
+
       class << self
         def transform_args(args)
           # Return a string literal as is for backward compatibility

lib/irb/cmd/finish.rb

@@ -6,7 +6,7 @@ module IRB
   # :stopdoc:
 
   module ExtendCommand
-    class Finish < Debug
+    class Finish < DebugCommand
       def execute(*args)
         super(do_cmds: ["finish", *args].join(" "))
       end

lib/irb/cmd/help.rb

@@ -16,6 +16,9 @@ module IRB
 
   module ExtendCommand
     class Help < Nop
+      category "Context"
+      description "Enter the mode to look up RI documents."
+
       def execute(*names)
         require 'rdoc/ri/driver'
         opts = RDoc::RI::Driver.process_args([])