Display a warning when command name collides with a local/method.

Warnings can be turned on/off by setting Pry.config.collision_warning = true/false. Defaults to true

lib/pry/command_processor.rb

@@ -101,6 +101,17 @@ class Pry
       [cmd_data, (Regexp.last_match ? Regexp.last_match.captures : nil), (Regexp.last_match ? Regexp.last_match.end(0) : nil)]
     end
 
+    # Display a warning if a command collides with a local/method in
+    # the current scope.
+    # @param [String] command_name_match The name of the colliding command.
+    # @param [Binding] target The current binding context.
+    def check_for_command_name_collision(command_name_match, target)
+      if collision_type = target.eval("defined?(#{command_name_match})")
+        pry_instance.output.puts "#{Pry::Helpers::Text.bold('WARNING:')} Command name collision with a #{collision_type}: '#{command_name_match}'\n\n"
+      end
+    rescue Pry::RescuableException
+    end
+
     # Process Pry commands. Pry commands are not Ruby methods and are evaluated
     # prior to Ruby expressions.
     # Commands can be modified/configured by the user: see `Pry::Commands`
@@ -123,6 +134,8 @@ class Pry
 
       arg_string = val[pos..-1]
 
+      check_for_command_name_collision(val[0..pos].rstrip, target) if Pry.config.collision_warning
+
       # remove the one leading space if it exists
       arg_string.slice!(0) if arg_string.start_with?(" ")
 

lib/pry/config.rb

@@ -138,6 +138,10 @@ class Pry
     # @return [Boolean] Whether or not indentation should be corrected
     #   after hitting enter. This feature is not supported by all terminals.
     attr_accessor :correct_indent
+
+    # @return [Boolean] Whether or not a warning will be displayed when
+    #   a command name collides with a method/local in the current context.
+    attr_accessor :collision_warning
   end
 end
 

lib/pry/pry_class.rb

@@ -206,6 +206,7 @@ class Pry
     config.command_prefix = ""
     config.auto_indent = true
     config.correct_indent = true
+    config.collision_warning = true
 
     config.plugins ||= OpenStruct.new
     config.plugins.enabled = true