DaedTech

Stories about Software

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Plugging Leaky Abstractions

Editorial Note: I originally wrote this post for the NDepend blog.  You can check out the original here, at their site.  While you’re there, download NDepend and play around with it.

In 2002, Joel Spolsky coined something he called “The Law of Leaky Abstractions.”  In software, an “abstraction” hides complexity of an underlying system from those using the abstraction.  Examples abound, but for a quick understanding, think of an ORM hiding from you the details of database interaction.

The Law of Leaky Abstractions states that, “all non-trivial abstractions, to some degree, are leaky.”  “Leaky” indicates that the abstraction fails to adequately hide its internal details.  Imagine, for instance, that while modifying the objects generated by your ORM, you suddenly needed to manage the particulars of some SQL query.  The abstraction leaked, forcing you to understand the details that it was supposed to hide.


Spolsky’s point may inspire a fatalistic feeling.  After all, if the things are doomed to leak, why bother with them in the first place?  But I like to consider it a caution against chasing perfection rather than a lament.

Abstractions in software help us the same way figurative language helps our prose.  Metaphors and analogies offer ease of understanding, but at the accepted price of lost precision.  If you press a metaphor enough, it will inevitably break down.  But that doesn’t render metaphors useless — far from it.

Thus, if you have a leaky abstraction, you can take steps to “plug” it, so to speak.  Spolsky says it himself, right in the law he coined: “all non-trivial abstractions are, to some degree, leaky.”  We have the ability to lessen that degree.

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The Developer Feedback Loop

Editorial Note: I originally wrote this post for the SubMain blog.  You can check out the original here, at their site.  While you’re there, check out some of the products that they offer, including GhostDoc and CodeIt.Right.

If you write software, the term “feedback loop” might have made its way into your vocabulary.  It charts a slightly indirect route from its conception and into the developer lexicon, though, so let’s start with the term’s origin.  A feedback loop in general systems uses its output as one of its inputs.

Kind of vague, huh?  I’ll clarify with an example.  I’m actually writing this post from a hotel room, so I can see the air conditioner from my seat.  Charlotte, North Carolina, my temporary home, boasts some pretty steamy weather this time of year, so I’m giving the machine a workout.  Its LED display reads 70 Fahrenheit and it’s cranking to make that happen.

When the AC unit hits exactly 70 degrees, as measured by its thermostat, it will take a break.  But as soon as the thermostat starts inching toward 71, it will turn itself back on and start working again.  Such is the Sisyphean struggle of climate control.

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Important for us here, though, is the mechanics of this system.  The AC unit alters the temperature in the room (its output).  But it also uses the temperature in the room as input (if < 71, do nothing, else cool the room).  Climate control in buildings operates via feedback loop.

Appropriating the Term for Software Development

It takes a bit of a cognitive leap to think of your own tradecraft in terms of feedback loops.  Most likely this happens because you become part of the system.  Most people find it harder to reason about things from within.

In software development, you complete the loop.  You write code, the compiler builds it, the OS runs it, you observe the result, and decide what to do to the code next.  The output of that system becomes the input to drive the next round.

If you have heard the term before, you’ve probably also heard the term “tightening the feedback loop.”  Whether or not you’ve heard it, what people mean by this is reducing the cycle time of the aforementioned system.  People throwing that term around look to streamline the write->build->run->write again process.

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Are You Changing the Rules of the Road?

Happy Friday, all.  A while back, I announced some changes to the blog, including a partnership with Infragistics, who sponsors me.  Part of my arrangement with them and with a few other outfits (stay tuned for those announcements) is that I now write blog posts for them.  Between writing posts for this blog, writing posts for those blogs, and now writing a book, I’m doing a lot of writing.  So instead of writing Friday’s post late Thursday evening, I’m going to do some work on my book instead and link you to one of my Infragistics posts.

The title is, “Are You Changing the Rules of the Road?”  Please go check it out.  Because they didn’t initially have my headshot and bio, it’s posted under the account “DevToolsGuy,” but it’s clearly me, right down to one of Amanda’s signature drawings there in the post.  I may do this here and there going forward to free up a bit of my time to work on the book.  But wherever the posts reside, they’re still me, and they’re still me writing for the same audience that I always do.

 

 

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What Story Does Your Code Tell?

I’ve found that as the timeline of my life becomes longer, my capacity for surprise at my situation diminishes. And so my recent combination of types of work and engagements, rather than being strange in any way to me, is simply ammo for genuineness when I offer up the cliche, “variety is the spice of life.” Of late, I’ve been reviewing a lot of code in a coaching capacity as well as creating and giving workshops on story telling and creative writing. And given how much practice I’ve had over the last several years at multi-purposing my work, I’m quite vigilant for opportunities to merge story-telling and software advice. This post is one such opportunity, if a small one.

A little under a year ago, I offered up a post in which I suggested some visualization mnemonics to help make important software design principles more memorable. It was a relatively popular post, so I assume that people found it helpful. And the reason, I believe, that people found it helpful is that stories engage your brain far more than simple conveyance of information. When you read a white-paper explaining the Law of Demeter, the part of your brain that processes natural language activates and decodes the words. But when I tell you a story about a customer in a convenience store removing his pants to pay for a soda, your brain processes this text as if it were experiencing the event. Stories really engage the brain.

One of the most difficult aspects of writing code is to find ways to build abstraction and make your code readable so that others (or you, months later) can read the code as easily as prose. The idea is that code is read far more often than written or modified, so readability is important. But it isn’t just that the code should be readable — it should be understandable and, in some way, even memorable. Usually, understandability is achieved through simplicity and crisp, clear abstractions. Memorability, if achieved at all, is usually created via Principle of Least Surprise. It’s a cheat — your code is memorable not because it captivates the reader, but because the reader knows that mapping what she’s used to will probably work. (Of course, I recognize that atrocious code will be memorable in the vivid, conversational sense, but I’m talking about it being memorable in terms of its function and exact behavior).

It’s therefore worth asking what story your code is telling. Look at this code. What story is it telling?

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What I Learned from Learning about SpecFlow

In my ChessTDD series, I was confronted with the need to create some actual acceptance tests.  Historically, I’d generally done this by writing something like a console application that would exercise the system under test.  But I figured this series was about readers/viewers and me learning alongside one another on a TDD journey through a complicated domain, so why not add just another piece of learning to the mix.  I started watching a Pluralsight course about SpecFlow and flubbing my way through it in episodes of my series.

But as it turns out, I picked up SpecFlow quickly.  Like, really quickly.  As much as I’d like to think that this is because I’m some kind of genius, that’s not the explanation by a long shot.  What’s really going on is a lot more in line with the “Talent is Overrated” philosophy that the deck was stacked in my favor via tons and tons of deliberate practice.

SpecFlow is somewhat intuitive, but not remarkably so.  You create these text files, following a certain kind of format, and they’re easy to read.  And then somehow, through behind the scenes magic, they get tied to these actual code files, and not the “code behind” for the feature file that gets generated and is hard to read.  You tie them to the code files yourself in one of a few different ways.  SpecFlow in general relies a good bit on this magic, and anytime there’s magic involved, relatively inexperienced developers can be thrown easily for loops.  To remind myself of this fact, all I need to do is go back in time 8 years or so to when I was struggling to wrap my head around how Spring and an XML file in the Java world made it so that I never invoked constructors anywhere.  IoC containers were utter black magic to me; how does this thing get instantiated, anyway?!

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