JVM settings when using Jetty via Gradle & Gretty

We're using Gradle, Jetty, and Gretty in a project. We'd like to use asserts and a native library... How do you pass in settings to your JVM?

You can do this in the file build.gradle, within the gretty block, using jvmArgs (which takes a list of strings), like this:

// Gretty
buildscript {  
    dependencies {
        classpath 'org.akhikhl.gretty:gretty:1.1.3'
    }
}
 
apply plugin: 'war'
apply plugin: 'org.akhikhl.gretty'

gretty {
    // supported values:
    // 'jetty7', 'jetty8', 'jetty9', 'tomcat7', 'tomcat8'
    servletContainer = 'jetty8'
    jvmArgs = ['-ea']
}

And that's enableAssertions set to true.

Not antisemitic only anti-Zionist?

If you're in doubt about whether antisemitism exists in Britain, read the Facebook page Everyday Antisemitism.

The Guardian's had some good articles recently on antisemitism in the UK, especially within the left-wing. The comments section (never read the comments) shows that the problem is real, and also that some people don't recognise offensive and antisemitic comments. So here is the EU's working draft definition of antisemitism.

There's obviously anti-semitic stuff, and then there's a grey area around Israel and Zionism, and this document has a reasonable go at delineating that. Summary: Criticism of Israel similar to that levelled against any other country cannot be regarded as antisemitic, but anti-Israel comments can be antisemitic.

Some people seem to feel that any anti-Israeli statement is fine as long as it doesn't use the word "Jew". That's problematic. Of course Israel can be criticised for e.g. its poor human rights record. But also it is possible to be racist about Israel and Israelis. To debate whether such comments are technically antisemitic or merely racist-towards-a-nation seems besides the point.

On the recent Labour Party problems, some on the left have tried to dismiss the issue, arguing that it is being used to unfairly attack Corbyn -- whilst Zac Goldsmith and the Tory Party can get away with running a really racist anti-Muslim campaign. I think this is true, but dismissing the issue is wrong. The problem of antisemitism is real, and should be addressed.

My own experience is I'm happy to say I rarely encounter antisemitism, but I have encountered it, and in leftwing groups (although there's a sampling bias there, as I rarely hang out with UKIPpers).

Note: This post was backdated from May 2016, because that is the way to set front-page ordering on this blog.

Broken by default: Java 8 is not quite backwards compatible

Java 8 introduces several nice features, one of which is the default keyword. This is close to having mix-ins (aka traits; inheriting code from multiple parents) which is great. It also lets you add new methods to an old interface without breaking existing implementations. Or that's what it's meant to do.

But Oracle have broken backwards compatibility.

It is an error for a class to inherit a default method from two parents. If that happens, then the class must override the default method to specify what happens.

But if the default method involves a Java 8 class, then implementing it will break your code for Java 7.

I encountered this because we have a class which implements both List and Set. It's now impossible to do that if your code has to work across Java 7 and 8. To work in Java 8, it has to implement spititerator(), but that will break Java 7 which knows nothing of the Splititerator class.

How Social Media Failed Scotland

We've just seen (and been part of) a great democratic event in Scotland -- the whole country engaged in politics culminating in 85% of the population voting at the referendum.

As we all know it was a close race with 55% voting No (pro-Union), 45% Yes (pro-independence). But that's not the picture you'd get from Twitter, where 90% of tweets were pro-independence.^[1]

That's a failure for social media -- a great debate took place, but not on Twitter where nearly half of the people were absent. Unwilling to take part in an unwelcoming space?

Age of voters does not explain this. An opinion poll taken on the day shows the No vote was strongest amongst older voters^[2], less of whom will be on social media. However the other age groups showed closer to an even 50/50 Yes/No voting -- nowhere near the 90%+ observed on Twitter. Even taking age into account, social media was one-sided in an unrepresentative way.

Social media worked fantastically for the Yes campaign. The stream of Yes posts helped to build and maintain energy, spread pro-Yes knowledge through the network, shore up support, challenge No voters' thinking, and create a peer group effect in favour of Yes. Undoubtedly, it helped Yes to close the gap towards almost winning. However that very success had a downside: The No voters were absent -- until polling. They largely stayed out of the online debates, and you can't influence people if they aren't engaged.

Cybernats and subtler

Much was made in the mainstream press of Cybernats, abusive Scottish nationalists active on social media. Having examined a lot of tweets, I conclude: Cybernats do exist, and in greater numbers than the equivalent unpleasant No-supporters (Unitrolls), but they were still a very small minority. There were also people who, though not abusive, were aggressive -- again relatively small in number and effect. Mostly people did, as Gordon Brown put it, "disagree without being disagreeable".

A larger effect was (I think) the self-reinforcing momentum that Yes built up, which closed down the space for No voters to speak. Although the Yes and No camps were roughly the same size, the Yes were more passionate. A spiral emerged, whereby Yes supporters received considerable community reinforcement online, hence building that community, whereas No posts received more disagreement and critical questioning, acting to deter them.

So it wasn't really the Cybernats or any form of foul play. Social media became welcoming to one set of people and off-putting to the other. The No voice was self-silenced by the dominance of the Yes voice.

What makes for better debates?

This brings out an inherent weakness in forum debates -- that if a position should become too dominant, that very fact acts to shut down debate, as the other parties quietly leave.

So how do we create spaces where debate can flourish? Comparing Facebook and Twitter, we see that privacy and community encourage people to speak their mind. Unsurprising, but worth learning from.

The problem with Facebook debates is that they easily become closed "bubbles", rather than open debates. Each bubble acts as it's own echo-chamber, with the illusion that everyone agrees. In this case, the debate cut across networks, so most people knew Yes & No voters. Even so Facebook's filtering algorithms quickly act to create bubbles-within-bubbles. Facebook tries to select things-you-will-like and filter out things-you-won't-like, which is great for seeing/avoiding cat photos, but it's not a formula for real debate. In other debates, you might never hear the other side's point of view.³

Is there a third way -- something which can combine the open knowledge sharing of Wikipedia with the community aspect of Facebook?

I have some vague thoughts on how this might work (drawing on ideas from Lucas Dixon, Colin Fraser& Ben Young's old KenYersel project, http://www.kenyersel.org/), but nothing concrete. Any suggestions?

---

[1]: Counting #voteno / #voteyes from 1st August, 89.2% of vote-x tweets were for Yes. Even this is actually an under-estimate of the Yes dominance. The #voteno tweets were disproportionately from outside Scotland, and there were also considerable Yes supporters jumping on the #voteno hashtag to reach-out-to / mess-with the No audience. Anecdotally, the picture was more balanced on Facebook, where greater privacy and friendship groupings created a more open debating space.

[2]: Summary results from Lord Ashcroft's poll of 2,000 people

[3]: See Gilad Lotan's fascinating analysis of social media activity around the recent Israel/Gaza conflict. Data analysis of how news around the Israel-Gaza war was handled in social networks. TL:DR; People talks to like-minded folk who reinforce each other's viewpoint. Few people hear what the other side is saying.

Picture from http://www.anticapitalistes.net/

Some useful Eclipse <-> IntelliJ key bindings

As a veteran Eclipse user working with IntelliJ, here are the key-bindings I'm finding invaluable.

A nice surprise: IntelliJ has a key setting which mimics much of Eclipse. So your fingers don't have to relearn everything:
In File->Settings->Keymap, choose the "Eclipse" key bindings

A few vital key combos are different though:

Auto-complete / fix
Eclipse Control+Space
IntelliJ: Alt+Enter

Open resource / type, for quickly jumping to a file
Eclipse: Shift+Control+R or Shift+Control+T
IntelliJ: "double shift" (hit Shift twice)

Documentation for the Educated Stranger

When you're documenting an object/method/variable, ask: What would a stranger -- who knows basic coding & a bit about our project -- need to:

• Get or make an instance of this object?
• Use a class or function?
• Edit this code?

Good documentation is invaluable. It enables new people to join the team, and it takes some of the pain out of code maintenance. It's a balancing act: It should be short yet clear. And of course, you don't want to spend too long on it.

The clearer you can make the code itself, the less documentation is needed (see the notes below on avoiding pointless documentation).
But: readable method and variable names alone are not enough to make code self-documenting.

Things to document:

• Assumptions a method makes about the state of things.
• Exceptions that may be thrown, and why.
• Parameters whose meanings aren't obvious from the names. But there is no need to document the obvious.
• Methods that may return null, and why.
• When parameters can be null, and what that means.
• Object lifecycle (i.e. how it is wired up and disposed).
• Typical calling patterns -- how methods fit together.

The SoDash/Winterwell House Style

• Prefaces you might use:
  
  • FIXME for we-really-should-do-this.
  • TODO for less urgent tasks.
  • ?? for questions / things your uncertain about.
  • NB for tangential notes, e.g. explaining why you didn't use alternative method X.
• You can sign comments tweet-style with ^name or ^initials.
• If you see code whose purpose or behaviour you can't understand, add a comment. E.g. "?? is this number a probability? ^DW April 2014"
• Use assert in java, or SJTest's assert() and assertMatch() in javascript as a way to simultaneously test & document in-code assumptions.

How not to document

It's not about the amount of JavaDoc / JSDoc. It's the quality. Here's an example of pointless documentation:

/** {Object} */
var displayData;   

/** Get the display data for the part. 
* @param {string} url The url 
* @returns {Object} the display data.
*/
function getDisplayData(part, url)

How weak is this?

1. There's no point in doc which just restates the function/variable name. You are not writing for idiots.
2. Type {Object} tells us very little! What kind of object is it?
   A common case is where Object is a lookup map, in which case
   say what the keys are. Consider using a name which clearly describes the lookup, e.g. tagsetFromTag is clear, whereas tagsets isn't.
3. Parameters: Can they be null? What happens if they are?
4. The input parameter url in this example is ambiguous: is this an absolute url, a relative url, or does it not matter because both will give the same output, or does it matter but which to use is specified elsewhere?
5. Return value: can it be null?
6. Lifecycle: when can this be called? E.g. does it only make sense after the page has done some initialisation steps.

---

Photo: Book sculpture by Daniel Lai, "Kenjio"

Welcome to my blog-site Platypus Innovation.

The platypus caused consternation, shattered existing categories. It's existence was undeniable, but how should taxonomic theory be adapted to accommodate this uncomfortable fact?

This blog is also hard to classify. It loosely follows the interests and activities of Winterwell Associates, but it also includes personal material. Topics are likely to range from business affairs to new media via abstract mathematics.

One purpose of this site is to test out some of Winterwell's web technology. This site will sync with my SoDash account, which unlocks some rather unique features, though you're unlikely to encounter them during normal browsing.

Where will this blog go? From humble acorns, great oaks grow. But what if we've planted peanuts by mistake? Or genetically modified acorns that will turn into Evil Oaks? Only time will tell.