Use a clean toplevel_binding by default.

lib/pry/cli.rb

@@ -131,7 +131,7 @@ Copyright (c) 2011 John Mair (banisterfiend)
   on(:c, :context,
      "Start the session in the specified context. Equivalent to `context.pry` in a session.",
      :argument => true,
-     :default => "TOPLEVEL_BINDING"
+     :default => "Pry.toplevel_binding"
      )
 end.process_options do |opts|
   # invoked via cli

lib/pry/pry_class.rb

@@ -46,6 +46,9 @@ class Pry
     # @return [Boolean] Whether Pry sessions are quiet by default.
     attr_accessor :quiet
 
+    # @return [Binding] A top level binding with no local variables
+    attr_accessor :toplevel_binding
+
     # plugin forwardables
     def_delegators :@plugin_manager, :plugins, :load_plugins, :locate_plugins
 
@@ -105,7 +108,7 @@ class Pry
   # @option options (see Pry#initialize)
   # @example
   #   Pry.start(Object.new, :input => MyInput.new)
-  def self.start(target=TOPLEVEL_BINDING, options={})
+  def self.start(target=toplevel_binding, options={})
     target = Pry.binding_for(target)
     initial_session_setup
 
@@ -359,4 +362,14 @@ class Pry
   end
 end
 
+# Grab a copy of the TOPLEVEL_BINDING without any local variables.
+# This binding has a default definee of Object, and new methods are
+# private (just as in TOPLEVEL_BINDING).
+def self.__binding_impl__
+  binding
+end
+Pry.toplevel_binding = __binding_impl__
+Pry.toplevel_binding.eval("private")
+class << self; undef __binding_impl__; end
+
 Pry.init

test/test_pry_defaults.rb

@@ -1,4 +1,5 @@
 require 'helper'
+version = 1
 describe "test Pry defaults" do
 
   after do
@@ -398,4 +399,28 @@ describe "test Pry defaults" do
       output.string.should == ""
     end
   end
+
+  describe 'toplevel_binding' do
+    it 'should be devoid of local variables' do
+      mock_pry(Pry.toplevel_binding, "ls -l").should.not =~ /version/
+
+      # https://github.com/rubinius/rubinius/issues/357
+      unless Pry::Helpers::BaseHelpers.rbx?
+        mock_pry(TOPLEVEL_BINDING, "ls -l").should =~ /version/
+      end
+    end
+
+    it 'should have self the same as TOPLEVEL_BINDING' do
+      mock_pry(Pry.toplevel_binding, "self.equal? TOPLEVEL_BINDING.eval('self')").should =~ /=> true/
+    end
+
+    # https://github.com/rubinius/rubinius/issues/1779
+    unless Pry::Helpers::BaseHelpers.rbx?
+      it 'should define private methods on Object' do
+        mock_pry(TOPLEVEL_BINDING, "def gooey_fooey; end")
+        method(:gooey_fooey).owner.should == Object
+        Pry::Method(method(:gooey_fooey)).visibility.should == :private
+      end
+    end
+  end
 end