Sunday, 10 June 2012

Undocumented feature - interrupt - part one

This is an undocumented feature that has been known about and used for a while, including a good guide on PUUU.  However, Compuware have documented a number of undocumented features in Uniface 9.5 and interrupt is not one of them.  This makes me think that there must be alternative ways of doing most of these things, or at least that's what I hope to determine whilst writing this post.

The most frequent usage, as far as I'm aware, is getting the working directory...

  working = $result

The way that interrupt works is that you pass in a numeric code in the first parameter which determines the functionality, and then the second parameter can be used to pass a value in if needed.  The output is then place in $result for you to do with what you need.  Of course, this example is no longer needed as there is now $ldir which returns the same thing...

  working = $ldir()

So clearly the new version is documented and therefore supported, it's also more concise code and easier to maintain.  So once again a familiar question pops into my head... Which performs best?  I tested both of them over 2,000,000 iterations...

  • interrupt = 00:07.31, 00:07.34, 00:07.36 (just over 7 seconds)
  • $ldir = 00:06.11, 00:06.09, 00:06.04 (just over 6 seconds)

So as you can see, $ldir also performs fractionally better.  Given the number of iterations, it's pretty negligible, but on top of all the other reasons, I'm convinced that I should be using it over the old interrupt method.

In the next part I will be going through each of the known interrupt codes, trying to find alternatives that are documented, and testing the performance where appropriate.

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