Format Display of Class Properties. Showing the date instead of the datenum.

I have a class I've created and one of the properties stores the time. It uses the matlab datenum type which is I suppose is actually just a number. What I'd like to do it when the contents of the object are displayed, I'd like it to format the specific time property as a datestr and not a number. I would like the value of the property to remain numeric just not displayed as a numeric.

Thanks in advance! Ryan