Make PlainBackend the default backend

Author: mrkn

iruby.gemspec

@@ -19,6 +19,7 @@ Gem::Specification.new do |s|
 
   s.add_dependency 'data_uri', '~> 0.1'
   s.add_dependency 'ffi-rzmq'
+  s.add_dependency 'irb'
   s.add_dependency 'mime-types', '>= 3.3.1'
   s.add_dependency 'multi_json', '~> 1.11'
 

lib/iruby/kernel.rb

@@ -50,7 +50,7 @@ def initialize(config_file, session_adapter_name=nil)
 
       @events = EventManager.new(EVENTS)
       @execution_count = 0
-      @backend = create_backend
+      @backend = PlainBackend.new
       @running = true
 
       self.class.events.trigger(:initialized, self)
@@ -84,14 +84,6 @@ def initialize(config_file, session_adapter_name=nil)
     # @see IRuby::Kernel.events
     attr_reader :events
 
-    # @private
-    def create_backend
-      PryBackend.new
-    rescue Exception => e
-      IRuby.logger.warn "Could not load PryBackend: #{e.message}\n#{e.backtrace.join("\n")}" unless LoadError === e
-      PlainBackend.new
-    end
-
     # Switch the backend (interactive shell) system
     #
     # @param backend [:irb,:plain,:pry] Specify the backend name switched to