def get_changes(self, factory_name, global_factory=False, resources=None,
                    task_handle=taskhandle.NullTaskHandle()):
        """Get the changes this refactoring makes

        `factory_name` indicates the name of the factory function to
        be added.  If `global_factory` is `True` the factory will be
        global otherwise a static method is added to the class.

        `resources` can be a list of `rope.base.resource.File`\s that
        this refactoring should be applied on; if `None` all python
        files in the project are searched.

        """
        if resources is None:
            resources = self.project.get_python_files()
        changes = ChangeSet('Introduce factory method <%s>' % factory_name)
        job_set = task_handle.create_jobset('Collecting Changes',
                                            len(resources))
        self._change_module(resources, changes, factory_name,
                            global_factory, job_set)
        return changes
Get the changes this refactoring makes

        `factory_name` indicates the name of the factory function to
        be added.  If `global_factory` is `True` the factory will be
        global otherwise a static method is added to the class.

        `resources` can be a list of `rope.base.resource.File`\s that
        this refactoring should be applied on; if `None` all python
        files in the project are searched.