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Ruminations. Reflections. Refractions. Code.

Jul 19, 2014 - software dev

Set If Not Null ‘Pattern’ in Java 8

When working with business entities, many of them will involve a mix of complicated logic, and plain CRUD data. Often we will have some update or create method where an incoming DTO or Request object will have a subset of fields to source details to update the target entity. Even when trying to restrict the scope of the DTO to what an operation needs (an idea I am a big fan of), it may still be course-grained enough for that scope, and still have nullable/optional fields. The resultant code will need to do null checks and decide what to source and what to ignore. Simple example:

 1class User {
 2  private String firstName;
 3  private String lastName;
 5  // ... getters ...
 7  // private setters
 8  private void setFirstName(String value) {
 9      firstName = value;  
10  }
12  private void setLastName(String value) {
13      lastName = value;  
14  }
16  public void update(UserDto dto) {
17    if (dto.getFirstName() != null) {
18        setFirstName(dto.getFirstName());
19    }
21    if (dto.getLastName() != null) {
22        setLastName(dto.getLastName());
23    }
24  }
26Digression: generally, I avoid public setters entirely.. business
27objects need specific business methods to manipulate/update them. We
28should stop (yeah... like since 2000 at least) thinking of them as
29anaemic wrappers of fields.
31However... private setters can sometimes be useful for encapsulating
32internal checks.

The issue here is with the null checks. Prior to Java 8, for simple values like Strings, there was no way to factor out the annoying null checks (well, not without more verbose artifacts like wrappers to create, or lose type safety and use reflection, blergh…).

What I really want to say is: setIfNotNotNull(fieldToSet, valueToUseIfNotNull).

Now, since String refs are immutable, we can’t pass them in to update in setIfNotNull(…), the local ref will simply be overwritten with a new value… enter our setters, which have a common format of void setFoo(T val). Making use of Java 8 Method References we can achieve what we want in a typesafe manner:

 1class User {
 2    // ...
 4    public void update(UserDto dto) {
 5        setIfNotNull(this::setFirstName, dto.getFirstName());
 6        setIfNotNull(this::setLastName, dto.getLastName());
 7    }
 9    // note the use of java.util.function.Consumer -- a suitable archetype
10    // for setter methods.
11    private <T> void setIfNotNull(final Consumer<T> setter, final T value) {
12        if (value != null) {
13            setter.accept(value);
14        }
15    }


Of course, you can use lambda expressions where we used method references, but in this case, the existing methods encapsulate the logic we need.

Now, to see how far I can take this… I am reminded of Simplicity, Clarity, Generality… it never ceases to amaze me that the timeless 3 traits, more often than not, support each other.

PS. to get up to date with Java 8, Java 8 for the Really Impatient does a stellar job. However, you will have to be patient in parts (I did anyway :P).

PPS. I am still coming to grips with Optional types, and hence have not mentioned this as an alternative to null checks.

PPPS. Sorry about using the term ‘pattern’, it was an attempt to sugar coat the phrase ‘crappy-as rote work’. (There, Tommy). 😛

Sep 18, 2013 - software dev

Cherry MX Mechanical Key Switches

Came across this article recently explaining the Cherry MX key switches used in mechanical keyboards. Very informative.

On mechanical keyboards, these are some interesting links:

  • Mechanical Keyboards Terms explains the various terminology used in describing properties of a mechanical keyboard. Look through this if you don’t get terms used in the Cherry MX article above.
  • Das Keyboard can be probably be credited as the company that brought the ‘cool-factor’ to mechanical keyboards. Aesthetically beautiful keyboards, too. They even allow selecting your Cherry MX switch, allowing blue, red, or brown. They have a Mac edition too for all you Mac owners.
  • WASD Keyboards sell mechanical keyboards with lots of customisation options!
  • CODE Keyboard is a more recent invention by Jeff Atwood (of Coding Horror and StackOverflow fame) putting together quite a few neat features, his dream mechanical keyboard. I like that it has a Dvorak dipswitch too! Interestingly enough, it uses the clear Cherry MX switches which is non-clicky like the browns, but has a higher actuation force. It went out of stock very quickly!

Now to decide between blue and brown (or clear… hmmm..)… do I want the noise or don’t I want the noise… dilemma, dilemma.

Sep 18, 2013 - general software dev

Team Enthusiasm and Productivity

A friend posted this HBR article on the transience of high-performing teams on his Facebook account. This got me thinking, and commenting… thought a blog post might be a better medium to express my thoughts.

Overall, I agree with the article, but I think it, possibly deliberately, does not consider what can be done in more corporate workplaces, where team members tend to stick around for about 2 to 3 years on average.

Keeping this premise in mind — I think the cause of complacency/comfort is doing the same thing over and over again. In many creative fields, this is recognised as an issue. I would say many more “corporate” fields are also “creative”, but not recognised as such, in particular (as it affects me), writing software. This has made real gains in those fields pretty elusive, and limited to a few select teams where the creative aspect is acknowledged, or obtained through accidental discovery then subsequently forgotten.

To me the answer to battling complacency is simple: there needs to be regular, short breaks, where you go do something different but related for a period. For example, explore some new technology, some new framework you think would amount to eliminating some pain point in your core product. Or write some experimental feature integrated into the core product even if there is no known business requirement for it. Or, write something orthogonal to the core product, a support tool. You get the idea: something that makes the employee happy even if there is no immediate business driver for it.

Digression: Speaking of business/customer drivers, it’s a good time to remember Henry Ford’s quote: “If I had asked people what they wanted, they would have said faster horses.” So customers are not the only people who gain insights into what they need. Neither is just management, nor just developers. That’s the point of a team — a collective hive mind.

Back to the core issue, ideally, these breaks need not be accounted for stringently — their purpose is intangible. To require say a short discussion of what one did is very reasonable, but to require that it produce something that adds to the bottomline directly is not reasonable IMV.

One might consider Google’s 20% time, but from what I gather (and I could be wrong here), that time is accountable and you MUST produce something which then feeds into employee performance reviews, etc. For me, that is a fallacy, and misses the point of this “productive downtime” idea I am proposing.

Complacency in my view is a form of mild boredom, and this implies being in a sort of shallow rut. To get out of ruts, people need to do something differently. Employers though are generally not creative enough, or brave enough to allow such measures, due to at least the following reasons:

  1. Trust: In some places, employee/employer relationships have a trust issue, say because in the past employers were bitten by employees abusing leniency. The reaction is human… but equally human is to get over it and not let one or two experiences taint one’s outlook for life.
  2. Excessive Sense of Accountability to a Board: A form of paralysis which forces management members to only ever make “safe”, mundane choices. Unfortunately, safe and mundane choices lead to safe and mundane results a lot of the time.

    I am not proposing constant risk taking — we need to ship and produce within reasonable timeframes… but there is no doubt that calculated risks and a willingness to be different in a positive way are behind some of the greatest successes.

    I would also argue one of the tasks of management is to be able to shield deserving creative people from the scrutiny of an uninformed board.

  3. Excessive Adherence to Best/Established Practice: At one point in time, slavery was established practice. It was a given. That’s how things were done. Was it right? I am all for properly backed studies, but they do not always apply. I also find there’s a bit of selective best-practice adherence, i.e. some places only use best-practices that will please management, but discard others that may in fact be required for the adopted practice to work! It’s like going on a diet without exercise, or exercising but keeping to your 30 Big Macs per night diet.

  4. Lack of Understanding of Staff Psychology: If employers are managing say, software projects (me biased? What bias?), it is necessary they understand the drivers and motivators of software developers. What makes software people tick exactly. I think here we have a generational gap problem too… many of us got into software because it was different, it has a joy of its own. But it is scientific, precise, and creative all at once; thus a lot of software developers suffer the same psychological issues as say artists and actors. Yet, we work under fairly corporate conditions. So there is a mismatch.

    This point is then inexorably linked to the point on Trust… how can you trust easily what you do not understand…

    Granted there are software developers that come with a sense of entitlement… just as there are managers that come with the same. That is an individual issue, the punishment cannot be applied to the whole species.

In my view, there are plenty of things employers can do to improve team morale (and thus output). It just takes some willingness, some creativity, some courage, and some trust.

Jul 14, 2013 - software dev

Linux Xorg Recovery Tip

When you screw up your X drivers, the following is a good way to force “safe” drivers, assuming you have a bootloader that allows you to edit your kernel boot params like grub.

  1. Boot into grub.
  2. Edit the boot entry removing extraneous video related entries like splashscreens, and use the following instead: nomodeset vga=791 forcevesa. Generally, depending on your graphics card, vga=791 forcevesa should do.

The tip was based on looking at the SystemRescueCD distro.

Additionally, so I get a more decent virtual console resolution for day to day use, under Debian I do:

  1. Edit /etc/default/grub
  2. Find, enable if commented, and set:
    1# The resolution used on graphical terminal
    2# note that you can use only modes which your graphic card supports via VBE
    3# you can see them in real GRUB with the command `vbeinfo'
  3. Run update-grub2

Dec 9, 2012 - how to software dev

Oracle JDK on Debian

Just came across JavaPackage in Debian. This allows you to cleanly replace OpenJDK with a complying alternative systemwide, the Debian Way. I was only interested in the Oracle JDK, and that worked a treat, not sure about other JDKs. In essence:

  1. Install the JavaPackage package using apt[itude]
  2. Download the .tar.gz JDK package from Oracle
  3. Run make-jpkg, installed as part of JavaPackage, against it (not as root); this produces a Debian package of the tarball
  4. Install the Debian package using dpkg
  5. Finally, use update-java-alternatives to update various Java-related symlinks systemwide. You can choose to only update a subset (e.g. just use the Oracle JDK for the browser plugins, but nothing else), or go the whole hog — all JDK binaries will then be from the Oracle JDK.

The wiki link has examples and details.

PS. I really miss saying “Sun JDK”.

Dec 9, 2012 - how to software dev

Android with Ivy and Ant

Created this template project because I wanted proper dependency management when developing for Android. I chose Ivy because it was the least intrusive, and Android officially supports Ant, which Ivy cleanly integrates with, rather than Maven.

Honestly, making Eclipse and Maven play with each other seems to be a really unnecessary time-sink for most things, it’s stupid. mvn eclipse:eclipse, in my opinion, is a much better approach than m2eclipse or similar “heavy” integrating plugins. Unfortunately, I could not find a similar thing for ADT. Anyway, Ivy is quite cool as a pure dependency manager once you (mostly) get your head around “configurations”.

Anyway, hopefully it is useful to others besides me.