Little-Known Fact: The IDL Workbench Keeps Backups of Your Edited Files

...and it helps you compare and revert changes, to boot!

Did you know that the IDL Workbench keeps backups of files you have edited, or that you can compare and merge versions of files?

The Eclipse platform (www.eclipse.org) used as the basis for the IDL Workbench has many built-in features by default.  IDL engineering has removed or hidden some because of their limited utility to most IDL programmers, but has left others intact.

The difference/merging (diff/merge) utility is one of the more handy, but it isn't well advertised.

Right click on a file you have edited and saved in the past week in your Project Explorer.  Scroll down the context menu and locate the "Compare With" item and select "Local History..."  Select one of the files listed.

Be amazed by the evolution of your mad coding skilz in just the past 7 days.

You'll be dropped into a diff/merge tool in which you can easily navigate to compare the files' contents and even merge modifications.  It's especially handy if your mad coding skilz have failed you and you need to revert to a less artful but more operational version of an algorithm.  I've heard.

Buttons in the upper right corner allow you to quite easily navigate through the differences in the files and transfer changes from one file to another.

The default history on any given file is maintained for 7 days.  To modify this time, in the Workbench select the menu item Window/Preferences.  In the subsequent dialog's tree navigate to General/Workspace/Local History and make any changes there.

The diff/merge tool is not limited to comparing versions of a single file.  It can be used to compare files or directories within a single project or across projects in your Project Explorer as well.  This is most useful if you keep separate projects for "managed" and "sandbox" source files, for a single code line.

Select a single file or folder in Project Explorer, then navigate to and control+left click a second file or folder.   Right click on one of the selected items to invoke the context menu and select "Compare With", then "Each Other".

If you're interested in learning more about where the local history data is stored for your edited files, search wiki.eclipse.org for the FAQ topic.