Original Post Date: Monday, July 11, 2011

There is a ton of code out there and we’re constantly adding more.  Gartner reported in 2009 that there were more than 310 billion lines of code in use worldwide. MS Word has grown from 27,000 lines of code in the first version to about 2 million in 2010.  The Windows Operating System grew from 3 million lines of code in 1992 to 20 Million in 1998.  You get the point – there’s lots of code out there doing lots of the same things that we may want our software to do.

One of the challenges software project leaders have in estimation and planning is successfully quantifying the functionality they can reuse and understanding and communicating the effort and cost associated with that reuse.  In projects where significant reuse is anticipated, reuse is really going to shape the project.  Reuse comes in many forms.  A firm grasp of the types of reuse and the potential pitfalls of such reuse facilities a thorough analysis of the impacts that reuse has on the project.  It is ill advised to expect to get a one to one benefit for reuse.  It is even more problematic to plan on reuse as a quick fix to schedule pressure.  


Some of the things you want to consider:

* Reusing legacy code can be a great productivity booster if the code is stable, well written and some of the original developers are on hand.  On the other hand, if you’re working with legacy code that has become spaghetti code which is only supported by a mildly deranged programmer in the corner cube – you might be better off starting from scratch
* The auto translation of existing code to newer technologies can also boost project productivity but one cannot expect the process to be transparent or without hiccups.  It is important to understand the nature of the translation tool, the amount of preparation required to use it and the expected amount of human intervention to make the translation complete
* The use of Commercial Off the Shelf Software (COTS) can significantly impact the schedule for a software project but there needs to be a thorough evaluation of the capabilities of the COTS against the requirements of the project.  There also needs to be acknowledgement with the consumer of the software system that using COTS software limits the amount of customization possible resulting in the risk that the finished product is not exactly what they expected.

Also it is often more complicated to integrate reused (not developed here) solutions since there is a steeper learning curve during the integration phase.  Code reuse can be a great way to achieve increased productivity but it is important not to assess this improvement over optimistically but rather through a careful appraisal of what the reuse activity entails.

Have a reuse story (success of horror) you want to share?  Post it as a comment to this blog.