Extends methods for the Context module
Evaluate the given command from the given load_file on the Context module.
Will also define any given aliases for the method.
 
               # File irb/extend-command.rb, line 237
def self.def_extend_command(cmd_name, load_file, *aliases)
  line = __LINE__; Context.module_eval %[
    def #{cmd_name}(*opts, &b)
      Context.module_eval {remove_method(:#{cmd_name})}
      require "#{load_file}"
      send :#{cmd_name}, *opts, &b
    end
    for ali in aliases
      alias_method ali, cmd_name
    end
  ], __FILE__, line
end
             
            Installs the default context extensions as irb commands:
Context#eval_history=
irb/ext/history.rb
Context#use_tracer=
irb/ext/tracer.rb
Context#use_loader=
irb/ext/use-loader.rb
Context#save_history=
irb/ext/save-history.rb
 
               # File irb/extend-command.rb, line 227
def self.install_extend_commands
  for args in @EXTEND_COMMANDS
    def_extend_command(*args)
  end
end