[ruby/irb] Suppress command return values

(https://github.com/ruby/irb/pull/934)

Since commands can't be chained with methods, their return values are
not intended to be used. But if IRB keeps storing command return values
as the last value, and print them, users may rely on such implicit
behaviour.

So to avoid such confusion, this commit suppresses command's
return values. It also updates some commands that currently rely on
this implicit behaviour.

https://github.com/ruby/irb/commit/fa96bea76f

3 files changed, 11 insertions, 6 deletions

diff --git a/lib/irb/command/chws.rb b/lib/irb/command/chws.rb
index e0a406885f..ef456d0961 100644
--- a/lib/irb/command/chws.rb
+++ b/lib/irb/command/chws.rb
@@ -15,7 +15,7 @@ module IRB
       description "Show the current workspace."
 
       def execute(_arg)
-        irb_context.main
+        puts "Current workspace: #{irb_context.main}"
       end
     end
 
@@ -30,7 +30,8 @@ module IRB
           obj = eval(arg, irb_context.workspace.binding)
           irb_context.change_workspace(obj)
         end
-        irb_context.main
+
+        puts "Current workspace: #{irb_context.main}"
       end
     end
   end
diff --git a/lib/irb/command/subirb.rb b/lib/irb/command/subirb.rb
index 138d61c930..85af28c1a5 100644
--- a/lib/irb/command/subirb.rb
+++ b/lib/irb/command/subirb.rb
@@ -49,6 +49,7 @@ module IRB
 
         extend_irb_context
         IRB.irb(nil, *obj)
+        puts IRB.JobManager.inspect
       end
     end
 
@@ -65,7 +66,7 @@ module IRB
         end
 
         extend_irb_context
-        IRB.JobManager
+        puts IRB.JobManager.inspect
       end
     end
 
@@ -90,6 +91,7 @@ module IRB
 
         raise CommandArgumentError.new("Please specify the id of target IRB job (listed in the `jobs` command).") unless key
         IRB.JobManager.switch(key)
+        puts IRB.JobManager.inspect
       end
     end
 
@@ -112,6 +114,7 @@ module IRB
 
         extend_irb_context
         IRB.JobManager.kill(*keys)
+        puts IRB.JobManager.inspect
       end
     end
   end
diff --git a/lib/irb/context.rb b/lib/irb/context.rb
index 836b8d2625..22e855f1ef 100644
--- a/lib/irb/context.rb
+++ b/lib/irb/context.rb
@@ -587,18 +587,19 @@ module IRB
 
     def evaluate(statement, line_no) # :nodoc:
       @line_no = line_no
-      result = nil
 
       case statement
       when Statement::EmptyInput
         return
       when Statement::Expression
         result = evaluate_expression(statement.code, line_no)
+        set_last_value(result)
       when Statement::Command
-        result = statement.command_class.execute(self, statement.arg)
+        statement.command_class.execute(self, statement.arg)
+        set_last_value(nil)
       end
 
-      set_last_value(result)
+      nil
     end
 
     def evaluate_expression(code, line_no) # :nodoc: