[ruby/irb] Print deprecation warning for `help` commandHEADmaster

(https://github.com/ruby/irb/pull/567)

* Give show_doc its own command class

* Print deprecation warning for `help` command

1 files changed, 48 insertions, 0 deletions

diff --git a/lib/irb/cmd/show_doc.rb b/lib/irb/cmd/show_doc.rb
new file mode 100644
index 0000000000..99dd9ab95a
--- /dev/null
+++ b/lib/irb/cmd/show_doc.rb
@@ -0,0 +1,48 @@
+# 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