Wednesday, October 25, 2017

Don't bother porting dead code


I have a task on me to move (we call it "port") some test code from one location to another.  The details are not interesting, but it did involve moving a test "Shape" object and a "Text" object.

The text object and the shape object both inherited from the same parent class, included the same set of header files, were co-located in the same directory within the project I wanted to modify and were otherwise similar in structure.  For a variety of reasons, though, the text object could be moved without much effort at all.  The shape object proved far more difficult.

At first, the compiler complained it could not find the header file for shape.h.  That was a little tricky, but it boiled down to having 2 files named shape.h in the project, and the path to the file I wanted was not specified correctly.  Fixing that caused the shape object not to be able to inherit from its parent class.

And thus began about 2 weeks of trying to get the darn code to build.  I would find and fix one problem only to get to the next error.  This is not unusual - we call it peeling the onion - but it is time consuming. 

For my needs, this is a medium priority task at best, so I wasn't working on it full time.  Just when I could fit it into my schedule for an hour or so.  I started with 27 build errors, built that up to about 100, then whittled it all down to 2.

But at this point I was 2 weeks into build files, linking errors, etc… and decided to try a new approach since I felt I was treating symptoms and not the underlying problem.

I put everything back where it was (reverted my changes, so to speak) and rebuilt.  I then stepped through the code to see how the Shape object was being allocated and used.

It wasn't.

Although it is referenced in the tests, it was never used.  It was dead code.

Sigh.

I was able to delete the dead code, move everything else I needed and got unblocked.

Lesson learned - do your investigation early in the process to determine what actually needs to be ported!

Now, off to a 2 week hiatus.  See you when I am back!

Questions, comments, concerns and criticisms always welcome,
John

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