Design and Implementation

One of the key tenets in good software deisgn is to separate the design of your product from it's implementation.

In some industries, this is much harder to do. When designing a physical product, the structural strength & capabilities of the material being used must be taken into account. There's a reason most bridges have large columns of concrete and steel going down into the water below. From a design perspective, it'd be much better to not have these pillars, thereby disturbing the natural environment less and allowing shipping to pass more easily.

Photo by NJScott. An example of design being (partially) dictated by implementation.

Once you start looking for places where the implementation has "bubbled up" to the design, you start seeing them all over the place. For example, my analogue wristwatch has a date ticker. Most date tickers have 31 days, which means manual adjustment is required after a month with fewer than 31 days. I'm prepared to live with this. However, the date ticker on my watch is made up of two independent wheels - and it climbs to 39 before rolling over, which means manual intervention is required every month! What comes after day 39? day 00 of course!

It's easy to understand why this would be the case - it's much simpler to create a simple counting mechanism that uses two rollers and wraps around at 39 than it is to create one that wraps at the appropriate dates. I have yet to see an analogue wristwatch that accounts for leap-years.

Software engineers have a much easier time; our materials are virtual - ideas, concepts and pixels are much easier to manipulate than concrete and steel. However, there are still limitations imposed on us - for example data can only be retrieved at a certain speed. Hardware often limits the possibilities open to us as programmers. However, these limitations can often be avoided or disguised. Naive implementations often lead to poor performance. A classic example of this is Microsoft's Notepad application. Notepad will load the entire contents of the file into memory at once, which can take a very long time if the file you are opening is large. What's worse is that it will prevent the user from using the application (notepad hangs, rendering it unusable) while this loading is happening. For example, opening a 30MB text file takes roughly 10 seconds on this machine. This seems particularly silly when you consider that you can only ever see a single page of the data at a time - why load the whole file when such a small percentage of it is required at any one time? I guess the programmers who wrote notepad did not intend for this use case, but the point remains valid: an overly-simple implementation led to poor performance.

The unfortunate state of affairs is that the general population have been conditioned to accept bad software as the norm. There really is no excuse for software that is slow, crashes, or is unnecessarily hard to use. It's not until you use a truly incredible piece of software that you realise what can be achieved. So what needs to change? Two things:
  1. Developers need to be given the tools we need to make incredible software. These tools are getting better all the time. My personal preference for the Qt frameworks just paid off with the beta release of Qt 4.7 and QT Creator 2.0. I plan on writing about the new "Quick" framework in the future: I anticipate it making a substantial difference to the way UI designers and developers collaborate on UI design and construction.

  2. Users need to be more discerning and vocal. As an application developers it can be very hard to know what your users think. If you don't get any feedback, are your users happy, or just silent? We need a better way for users to send feedback to developers; it needs to be low-effort fast and efficient.