When writing Java servers (or servlets that run in a container), I’ve learned a few things that have saved me a bunch of trouble during development, as well as later on.

Dependency Injection

• Injection: if something is singleton (request, global or any other scope), the only things injected to it should also be singleton – otherwise you get implicit singletons of things the singleton holds, and may not be what you want – and generally harder to reason about. Better to have the singleton instances be leaves in the tree of injected things.

I think that most people would agree these days that dependency injection is a good thing for many reasons.

• It allows you to decouple concrete classes from each other
• It makes for a uniform method of object construction
• It simplifies plumbing
• Makes it easier to make testable classes

The problem that I have with it is that, at least in Java, the main frameworks for doing it, being Guice and Spring, can sometimes be as bad as the problem DI tries to solve.

When starting as a software developer, everything seems like magic, compilers, IDEs, networking, kernels, etc. While we can ignore how these things work, to really grow as a developer, the magic must be removed. At the end of the day, our job is to produce something that works, having a well-rounded knowledge of how the full stack works can help you to understand when weird stuff happens, and come up with useful theories as to what is going on. Much as when I was a kid, I tended to take things apart to see how they work, and most times was able to get it back together; apologies to my Dad for the barometer/thermometer pieces he found one day. Here are a few things you might consider doing to “take things apart” and remove the magic.

Background

I started my professional career with a Pascal program (I know that dates me a bit) and then continued with C and C++ and discovered Python around version 1.4 and used it heavily for over ten years, and really didn’t like Java when I first met it (version 1.3-1.4 time frame).

I’ve also used a ton of other languages for real deployed projects, like Python, Ruby, C, C++, Common Lisp (which I <3 love), C#, Clojure, Visual Basic, and Go, so I’m a not the average “blub” programmer saying this.

I’ve not done a ton of programming in Python for a while, but I still do like the language. I also like trying to do things in one line (ok, one statement), just because it’s a bit more difficult :). These are pretty old, but I used to keep these in my email signature line…

Mandlebrot set

#this one really only works if your terminal window is 80 wide
import os;map(lambda i:os.write(1,chr(reduce(lambda(z,t),o:abs(z*z)>4and(6,
t)or(z*z+o[0],t+1),[(i%80*.04875-2.6+i/80*2.8j/26-1.4j,65)]*31)[1])),range
(2080))

The screen of e

AKA Good Programmers Are Doing Real Science

There are a bunch of long-ish winded definitions of the scientific method, but I think a reasonable pithy description would be:

1. Come up with a theory to explain an existing phenomena.
2. Use that theory to come up with a falsifiable prediction.
3. Conduct experiments to prove or disprove the truth of the prediction.
4. Independent parties repeat #3 and reproduce the results.

Now if the experiments at step three or four disprove the truth of the prediction, one of a few things can happen:

When dealing with the problem of a long method, the simplest thing you can usually do is to break it into it’s conceptual pieces and have a series of tail called functions that call the next chunk of the computation.

So given this:

private Thing methodThatIsTooLong(TypeThing arg1, OtherType arg2) {
   // chunk1
   // chunk2
   // ....
   // chunkN
}

You get:

In The Cult Of Abstraction I railed against the over-use of abstraction. Here, I want to talk about a particular source cause of over-abstraction I have seen (and been guilty of).

Recently, while working with another team here at Spotify, I was working through some of their test code using the Helios Testing Framework, and the harness used a surprisingly complicated tree of classes to set up the various containers it used.

While I’m often at odds with software frameworks (libraries are to be preferred over frameworks, generally), I’ve found that process frameworks can be very good indeed, when done right. Implementors of agile methodologies ironically can fall into the trap of doing it wrong.

Why ironic? Well let’s look at the agile manifesto from the agile manifesto website:

1. Individuals and interactions over processes and tools
2. Working software over comprehensive documentation
3. Customer collaboration over contract negotiation
4. Responding to change over following a plan

What I’ve heard is that in many companies they prescribe: “We do agile this way”, which breaks the first statement of agile. On the other hand, when agile is done right, if you have many teams, you should have many variants of agile processes. If you are going to prescribe something, it’s best to prescribe the framework, i.e. the manifesto, rather than it’s particular implementation.

I’ve known handywrite shorthand for a number of years, and finally decided that I should learn shorthand proper, ideally with the best bang/buck ratio, as well as minimal amount of initial learning, with being able to ramp up the amount I learn later, as time permits. I settled on Gregg shorthand, Anniversary Edition.

In hunting the net in the hopes of learning Gregg, I’ve found a bunch of PDFs that I’ve found helpful. As far as I’ve been able to tell, all of them are out of copyright and/or directly linked. If anyone finds different, please let me know. The ones I was able to figure out where I got them are linked, with local copies (when I believe permitted) in the event that the target site goes away.