Robust modification of persistent objects while preserving formatting and other attributes

Abstract

A method and system for preserving attributes of objects within a file that was created in a different environment from that in which the file is opened, enabling the attributes to be maintained after the file is saved. For example, an HTML document created with a text editor includes elements such as plain text and HTML tags, with which attributes such as whitespace, line breaks, and indent level are associated. When such a document is opened in an HTML editor implementing the present invention, the attributes of these elements are preserved. Even when changes to these elements occur, to the extent possible, the method provides for determining attributes of related elements that were in the document as originally opened in the HTML editor, so that these attributes can be applied to corresponding objects that are added to the document or in regard to changes that are made by the user. The preservation of persistent object attributes is also applicable to other types of software applications such as language development systems and word processing programs. This invention thus insures, for example, that functions developed in newer versions of a program, although not recognized in an earlier version, persist when a file is opened in the earlier version and then saved.