John Domingue wrote: > I would like to convey to a non-computer scientist > audience the significant effort that goes into software production in > order to motivate software and component re-use. Otherwise a naive > person may ask "why not just create the software you need on demand > every time?".
I've been thinking about this core question. I wonder whether you're looking for answers along the lines of: - it took 3,000 hours at a cost of 300,000 to build [x] - it took 300 hours at a cost of 3,000 to build [y] which reused code I've been a software developer since 1989 and have been doing the plans and costs for my own Internet company since 1995. If re-use means copying code from one program to another, I am hard pressed to think of any examples where re-used software affected the price quoted to the client. To explain: 1) the client owns the software developed Usually the client owns what they pay for unless the contract says otherwise. Developers can only reuse code for future projects for the same client. 2) is a call to an existing function "re-use"? I've been the PHP developer for the-racehorse.com since 2006 and have produced over 30,000 lines of code. However, I'm calling some functions written earlier in new code? Is that counted as re-use? 3) is using an open-source CMS code "re-use"? the-racehorse.com is built on Drupal. Drupal is an open-source CMS core with modules (functionality add-ons) developed by the community. Is using an extendible CMS "software re-use"? We used Drupal for the-racehorse.com because the client wanted a site within a few weeks. We previously built sites from scratch. The site we launched in time - and my first module was based on an existing module by someone else - but subsequent additions to the site have always been constrained by how Drupal works. Some additions we haven't been able to do at all because they'd take too long within Drupal. The trade-off HAS ALWAYS BEEN: a) write from scratch for more time/money for ultimate flexibility b) customise an off-the-shelf solution for less time/money for narrow flexibility As soon as you want to make an off-the-shelf system do something other than what it's intended, you spend MORE time/money than if you'd built the thing from scratch. Given the same requirement, approach (a) and (b) could end up costing the same in the long term. 4) Is using a CMS "re-use"? This year I'm working as a contractor as "Drupal Developer". Drupal 6.* is such that most site builds consist of going through configuration forms created by third-party modules. I'm working on a multi-lingual site but I've only written 500 lines of code and that's for managing custom login with cookies. I don't think that spending days installing and configuring modules in forms is development. But is it software re-use? 5) Fashion changes Over time, people's choice of programming language evolve. PHP, Python, Ruby on Rails, Java, you name it. Software re-use presumably assumes a consistency of language. My feeling is that commercial Internet projects get redeveloped every few years. John, I'd still like to know what kind of an answer you were hoping for with t > I'm looking for pointers to how much time and cost is associated > with producing software code. "3 weeks and 4,000 pounds" is an answer to that question. But would it have been useful? Or is the "pointers to" key? Paola -- http://www.paolability.com/ -- The Open University is incorporated by Royal Charter (RC 000391), an exempt charity in England & Wales and a charity registered in Scotland (SC 038302).
