Every programmer, at some point in time, needs to have a visual file difference application under their belt.  There are a number to choose from for various operating systems and either free or commercial.

Here's a short list of some of the ones that are available:

• Araxis Merge
• BeyondCompare
• DeltaWalker
• WinMerge

Of course a search on file difference tools will lead you to a plethora of other solutions.  The list provide are actually applications that I have tried with a prerequisite that they must also support performing folder differences.  There are many other tools around that only do file difference (and well I might add), but when conidering that you may be using such a tool in conjunction with Joomla! development, then folder differences are a must.

WinMerge is a free (and GPL) application for Windows but BeyondCompare was certainly my tool of choice for this platform and it was very reasonably priced (it's still around US$30 which is what I paid for it many, many years ago).

Since moving to the light, I mean the Mac, finding a good difference tool was a challenge.  There are, I believe, only two serious contenders in the Mac space: Merge by Araxis and DeltaWalker by Deltopia.  Both of these applications are commercial.

Merge has a standard edition at US$129 and a professional edition at US$269 at the time of writing.  The main difference between the two is the ability to do three-way merging in the professional eddition.  Bulk discounts are available as are discounted support renewals.

DeltaWalker has some extra flexibility in terms of purchasing either its Standard or Oro versions.  Like Merge, the Oro version gives you three-way comparisons and a few other things.  You can purchase a personal license for Standard for US$39.95 or the Oro for $79.95.  This gives you one year of updates and support.  Commercial licenses and bulk discounts are also available, if that is applicable to your business, but these are more expensive.

I road-tested both and finally settled on DeltaWalker (the Personal Oro version) for giving the best value for money overall.  It lacks some features of Merge and BeyondCompare, but it makes up for those in many other ways.

DeltaWalker is built on the Eclipse IDE platform so it is available for Mac, Linux and of course Windows.  This was pretty cool because Eclipse itself is my IDE of choice, so the familiarity it brings is nice.

I use this application more or less on a daily basis.  Here is a summary of the things I like about the application:

• File comparisons open in a tabbed pane, so you can quickly skip between several file pairs (that was very cool).
• The file comparison windows are actually fully fledged Eclipse editor windows so you can do almost anything in there that you'd normally do in the IDE. I find this particularly useful for doing a regular expression search and replace over multiple (and usually annoying) differences - this usually brings the difference alerts down to a reasonable number. This feature really alone excels compared to Beyond Compare and Merge.
• Copy to the "other side" is quite intuative and easily allows you to remove and add blocks as appropriate.
• The scrolling in the file comparison window is smart, with the connectors between difference blocks moving to sensible locations as you scroll.
• Typing paths will bring up a list of suggestions for the next file or folder names.
• It has a good range of selection options (show same, show different, show added, show deleted).
• Comparisons between folders and archive (zip) files, or even direct comparison of two archive files.
• The Oro license covers one copy of the application on each of the platforms supported (great value).
• Most importantly, the developers are easy to contact and very responsive to email requests and suggestions. That's always a good sign.

As I said, there are a few things I miss from my Windows days, like:

• There is no ability to save sessions (next version though - horray!).
• You can select two files of different names and compare them, but this will open up two file comparison tabs (with the left and right sides blank respectively). You can copy the path of one side to the other tab, but it would be nice to just open the two files up to be compared together in the one tab.
• A right-click then "Set as base folder" would be useful in my view. This was a useful feature in Beyond Compare.
• Beyond Compare has the ability to put in manual align marks. I think this would be useful because DeltaWalker doesn't quite get some of the lining up the way I would like it, but I also understand this would probably nasty to implement. While a nice to have, it's something I can live without.  Having a full editor available more than makes up for this.

I'm happy to say this list is steadily growing smaller as new versions are released.

DeltaWalker is a worthy replacement for Beyond Compare for when I was working on Windows. In fact, if I ever did have a momentary lapse of reason to go back to Windows land, I think I would be taking DeltaWalker with me.  Nah, that'll never happen.

For more information on Andrew, visit his profile page at community.joomla.org.