Wednesday, January 30, 2013

Code should be immutable

Change by addition, not mutation. Putting the open-closed principle into practice.

If I write a unit test and some code that satisfies that unit test, I should be reasonably confident that I will never have to change that unit of code again. I may add more units of code and I may delete old units it as soon as they become redundant, but I shouldn't put myself in a position to have to mutate an existing unit of code.

Within reason of course. Units of code aren't always atomic enough for this guidance to be considered a standard. The law of diminishing returns applies - be pragmatic in anticipating the ways the program will be required to change and pay particular attention to the probable extension points and axes of change.

I've realized a few benefits of this approach:
  • New code has fewer dependencies. I have much less risk if I introduce something new than if I modify something that exists.
  • I can have more control over when I replace an existing unit with a new unit. For example, I can run both side-by-side and compare their performance.
  • It helps me maintain a consistent velocity. Since the side effects of new code are less than changing existing code, I run into fewer unexpected problems and edge cases.
  • It gives me feedback on my code organization. If I cannot take this approach, it tends to be a good indicator of a violation of the single responsibility principle or proper encapsulation. It also means that in the future, I'll be spending all my time changing existing code to add new features and my velocity will tank.
  • I feel more creative when coding. Creating new code is more fulfilling than modifying existing code.


Some things need to be in place for this to happen successfully:
  • As mentioned above, strong and consistent application of the single responsibility principle and open-closed principle.
  • Good discipline in ensuring the units of code are of the right size. Typically it's smaller than a class, but bigger than a method. Perhaps a nested class.
  • Ability to swap an old unit with a new unit with minimal mutation (doesn't have to mean IoC - just reduce the proliferation of the unit).
  • Ability to flag redundant units for safe removal and the discipline to actually remove them.
  • Ability to measure the ratio of mutation to addition/removal and see it trend in the right direction.

Go ahead, try it on a small scale and see how you feel. Does the artificial restriction of not being able to modify your existing code cause you to think more about your design? Does it hurt your velocity or help maintain or improve it?

Keen observers will notice that this is just a spin on well established OOP principles (SRP and OCP). What I find fascinating is that code and the systems it's contained in are like fractals... the principles and hence the way they look is the same from any level of zoom.

Wednesday, January 23, 2013

What does the web mean to me?

The web to me is not the browser. It's not REST, it's not JavaScript. It's not Facebook, nor is it Twitter. The web, to me, is the fact that I'm writing this blog post offline and on my mobile phone while on the subway home*.

Two concepts embody the web to me: seamless computing and graceful handling of occasionally connected scenarios.

Seamless computing (sometimes called "the cloud" in nontechnical contexts), is the notion that my profile and my data are accessible and understood no matter what device I'm on. My email appears on my computer and phone. My music appears on my home theater and my portable music player. My eBooks appear on my eInk device and my phone. Hell, my thermostat is even on my wall and my phone!

Dealing with occasionally connected scenarios is a bit trickier, but oh, so, necessary. A contrived example is that I don't need to be online to read my eBooks. A slightly more thoughtful example is how I'm authoring this post offline. An often overlooked scenario is: Do I need to be online to search? 

With many of today's "instant search", the answer is "yes" and there is no graceful fallback for offline scenarios. What would a graceful fallback for search when offline look like?
  • Capture and save my search criteria
  • Wait until there is a connection to execute the search
  • Notify me asynchronously that you have results for me

Is that a useful use case? It's better than nothing. Maybe I'm out and about in a land of roaming charges and I see something I'm interested in that I want to research later.

I hereby redefine the term "world wide web" to mean any set of loosely coupled applications that enable seamless computing and rich occasionally connected experiences. The browser is just another application in that ecosystem.

* Yep, all text was written on my Galaxy Nexus during my 1h commute home. In true tradition of seamless computing, formatting and linking was performed on my laptop via the blogger web interface while connected. The right tools for the right job at the right time all working together. This is my web.

Sunday, January 13, 2013

Quick comprehension and information density

I've become a big fan of the PechaKucha format for almost all types of presentations. I'm also a fan of bite-sized information from other sources like the Khan Academy and MinutePhysics - the barrier to entry for complex topics is low and I highly recommend that you check them out. I find that my attention rarely wavers from the topic being discussed - primarily due to the time constraints and talent of the presenters.

I've been inspired to incorporate some similar principles into other formats (technical documents for example). It's a fun challenge for the author to work within these types of constraints and the benefits of a focused and understanding audience should be obvious.

Here is what I set out to achieve, whether I'm giving a presentation in 20x20 format or authoring a high level design document:
  • Keep the audience focused
  • Ensure high information density with no filler
  • Ensure a high amount of cohesiveness within the topic being discussed
  • Aim to gain comprehension in a short amount of time as possible

The 20x20 format (20 images, 20 seconds per image) provides a really good framework for guiding the author to the goals outlined above: You're forced to focus on the topic, you have a limited amount of time to discuss the topic (6 minutes), and you have a limited area to visualize your concepts (20 images).

For technical documentation (like high level software architecture documents), here are some constraints I'm going to try imposing on myself and my team to gauge how effective it is. A document must:
  • Be able to be read and understood in under 15 minutes. This constrains the length of document.
  • Be highly cohesive - all parts of the document must relate to the central concept being discussed.
  • Be independent - while it's OK for the document to reference other documents, reading those references must not be a requirement to the understanding of the topic of the document being read.
There are parallel's here to good code design (e.g. single responsibility principle or highly cohesive, loosely coupled classes). I'm not sure if that's a coincidence or a sign of a universal guideline of the universe!

Like the 20x20 format, there will be challenges for authors to trim complex concepts down to these formats, but it's a worthwhile quest as the benefits are very large indeed.

I can't wait to attend my first organized PechaKucha event here in Toronto later this month.

Tuesday, January 8, 2013

Structured decision making

Making decisions that involve multiple possible options and multiple stakeholders is hard. It's hard because it's usually done in an unstructured way, typically involving a never ending cycle of "pros & cons" that seem to get you into analysis paralysis until somebody makes an "executive decision" just because you've run out of time. As a consultant caught in the middle of a number of key decisions, I've come to rely on a process that I've derived from some structured thinking principles to reduce the time needed to make an informed and consensus-building decision.

Friday, January 4, 2013

Enterprise Information Management

Information management is difficult in any form, but there's no shortage of tooling to try and address the needs. My own needs are probably a subset of true ECM, but here are some of the more basic ones I would like to see. The main categories I care about are the authoring experience, the content features, the reading experience and the organization and ability to discover information.