<select class="selectTitle" id="C5" name="C5">
  <option value="">--select--</option>
  <option value="1">Mr</option>
  <option value="2">Ms</option>
  <option value="3">Mrs</option>
  <option value="4">Miss</option>
  <option value="5">Doctor</option>
  <option value="6">Judge</option>
  <option value="7">Professor</option>
  <option value="8">Councillor</option>
  <option value="9">Madam</option>
  <option value="10">Mr &amp; Mrs</option>
 Read the rest of this entry »

Reading this blog post, Destructuring binds in Ruby just now reminded me of a feature I love about Prolog which I wish would make it into other languages.

Firstly, I love assigning a list to a list of lvalues i.e. variables; this is possible in both PHP and Perl which I use regularly; and no doubt many other languages. (But not Java: why not!?)

    ($a, $b) =      ($b, $a);  // Perl
list($a, $b) = array($b, $a);  // PHP

PHP, as always, wins in inelegance, having the left side syntactically different to the right side. While it’s obviously the case that a list of values and a list of lvalues are technically different, I don’t think this difference should be expressed in the syntax.

I mean, in most languages you write e.g. $foo=4 and $bar=$foo; in both those cases you write $foo but yet they do something different (lvalue and rvalue); given that you write them the same there i think the same should apply to lists.

But I digress – What I want to mention is using “underscore” to mean “any variable”. I first saw this in Prolog.

For example, imagine you have to implement an interface (e.g. in Java), it requires you to write a function taking two parameters, but one of the parameters you don’t care about. Wouldn’t it be nice to write

interface ExistingApi {
   public void createObject(String name, Object otherInformation);
}

class MyInstanceOfTheApi {
   public void createObject(String name, _) {
      ...
   }
}

i.e. this shows clearly you do not care about the second parameter.

In current Java (and all languages I program including Perl, PHP) you have to give all variables a name even if you don’t use them, either in function definitions or in “assign to a list” scenarios mentioned above. It is then left as an exercise to the reader to determine if these variables are used or not, and indeed an exercise to the writer to name the variable they are never going to use.

I mean yes, technically you can actually just call variables “_” (or “$_” (except in Perl where “$_” already means something)) but that would then be a coding convention as opposed to a language feature, and who knows if the coding convention is actually used correctly by a programmer. (If “_” is a variable there’s nothing stopping someone from using its value.)

And then you have the problem if you have two variables you don’t care about, you can’t call them both “_”.

By the way, Programming in Prolog is an excellent book.

I just had the problem I’d placed a script into /etc/cron.daily on my Debian Lenny system but it wasn’t getting run (or at least it didn’t seem so).

Two things I learned:

(1) Execute the following to see which scripts would get run:

run-parts --test /etc/cron.daily

(2) In my case, the reason the script was never executed was that I called it “xyz.sh” as it was a shell script; the dot in the filename was the problem. I removed the dot and now it runs.

Between Java 1.0 and Java 1.3 (1996-2002 according to Wikipedia) there was no way to split strings into an array or a list.

In Java 1.4 the authors of Java saw it fit to introduce a method to split strings,

String csvData = "field1,field2,field3";
String[] fields = csvData.split(",");

However they did not introduce a method to “join” strings! Even in Java 7 there is no way to do this, e.g. via a static String.join method (2002-now).

OK I realize this is not “rocket science”, and I appreciate it exists in various versions in various third-party libraries, but still, it’s something every program needs to do at some point, it’s annoying to have to re-define it or think about it for each application.

For example, in one project I was working on in the last 6 months, such a function was created, and then had a bug! (OK but to be fair, that was not the only bug in the application!)

Come on, I mean this is a totally trivial function, totally necessary, available in all scripting lanuags why is it still not in Java?!

(P.S. Want to see an “enterprise java” solution to this problem? Check out the number of methods on this class)

In Java 1.4 there was the function Arrays.asList. You could pass it an array and it would make a list out of it.

String[] myArray = new String[] { "foo", "bar" };
List myList = Arrays.asList(myArray);

In Java 1.5 this was retrofitted for varargs; you could simply pass elements to the function

List<String> myList = Arrays.asList("foo", "bar");

I never really understood how that worked in a backwards-compatible way; I mean either the function takes an array of stuff, or it takes individual elements, surely?

It turns out, that with the varargs syntax, the caller is not forced to pass individual elements, the caller can instead pass an array of elements.

List<String> myList = Arrays.asList("foo", "bar");
List<String> myList = Arrays.asList(new String[] { "foo", "bar" });

The above two calls are identical, both return a List<String>.

But surely this is really dangerous? I mean Arrays.asList does not make any assumptions about what types of arguments it accepts; the list can be composed of any object.

How can it be certain that you want to have an List of Strings, and not a List containing a single element which is a String array? (An array is an object.)

To demonstrate this inconsistency:

String[] arr = new String[] { "foo", "bar" };
Arrays.asList(arr);            // returns List<String>
Arrays.asList(arr, arr);       // returns List<String[]>
Arrays.asList(arr, arr, arr);  // returns List<String[]>

Most modern languages use very similar syntax inspired by C; but the features added since C are really non-standard! The “for-each” syntax annoys me particularly. I mean none of these is significantly better/worse than the others, but I program in all these languages (apart from C#) on a regular basis and I always have to think when typing in the line in order not to get the wrong syntax.

For what it’s worth, I think “foreach” is nicer than “for” as it reads more like a sentence (the word “for” really makes no sense at all in that context); and about “in” vs. colon I’ve got no preference really.

I just read this excellent article relating to the reasoning for using NoSQL databases being performance problems.

http://thoughts.j-davis.com/2010/03/07/scalability-and-the-relational-model/

However, I wonder if it’s even reasonable to search for solutions to performance problems with the relational model; NoSQL, etc.

I think as computers get faster and faster (CPUs, SSDs, more memory, …) the set of problems which are “too slow” for a particular technology (or mindset) get fewer and fewer.

I used to have the pleasure of having to optimize systems (based on SQL, some of our solutions involved leaving the relational model); e.g. community with 4M users (uboot.com), but nowadays I have no customer where even an open-source database installed on reasonably inexpensive hardware is insufficient.

Of course, that’s just my experience, and there certainly are many problems, companies, etc. today which require solving performance problems in the database, but I assert a lot of the people proposing NoSQL as a solution to performance problems with SQL databases don’t have the performance problems in the first place; I mean not everyone is implementing Facebook, Google, …

How annoying, I upgraded from Debian Etch (Apache 2.2.3-4) to Debian Lenny (Apache 2.2.9), and then my Subversion Server (over HTTPS) gave the following error when surfed to from Firefox, which worked fine before:

An error occurred during a connection to svn.example.com.
SSL received a record that exceeded the maximum permissible length.
(Error code: ssl_error_rx_record_too_long)

What does that mean!? There’s not a great deal of info on the web.

Fundamentally, in my case, the first thing to work out, is that that error message means (or meant, in my case at least) HTTP was being transmitted over the HTTPS port, i.e. it wasn’t valid HTTPS at all, thus the protocol error. This could be confirmed by surfing to http://…:443/ (i.e. not https://) and seeing that the content (the Subversion server in my case) was correct.

The question was why? I had a bunch of sites in the “sites-enabled” directory, and another one of them (not my Subversion site!) had a

<VirtualHost *>

whereas it should have been

<VirtualHost *:80>

i.e. the port was missing. I’m not quite sure why it had that effect, as the request to the Subversion HTTPS URL did deliver the Subversion content, just not over HTTPS any more. But perhaps without the :80, it decided all ports should be subject to NameVirtualHost, and as that’s not possible with HTTPS, switched HTTPS off for all ports and all sites?

Nightmare ….

See also: http://stackoverflow.com/questions/119336/ssl-error-rx-record-too-long-and-apache-ssl

At approx 6:30am on Monday 21st Feb 2000 my boss, my colleague and I took the first version of Uboot online.

It certainly didn’t have all the features it needed back then, it took us one extra week to add an address book to the messaging functionality, for example. And it didn’t have any photo sharing, video sharing, blogging, or the e-commerce functions that it has now.

It’s actually amazing how fast we did develop the first version: a team of three software developers, I started at the company on 3rd Jan 2000 and completed two other projects before starting Uboot; the first commit was on 19th Jan 2000.

With a few exceptions, I have been involved with Uboot software development, sometimes more, sometimes less, since then.

Computers, if they are addressing the user, should address the user as “you”, not as “me”.

Computers need, from time to time, to address the user, for example “You have updated your setting successfully”.

Some programs use the word “you” to address the user, some use the word “me” on the grounds that the user is reading it, and to them, they are “me”.

However, using “me” to address someone is ridiculous! That’s as logical as a human using the word “I” or “me” to refer to the recipient of a piece of communication, “hey, do I fancy going to the pub?” on the grounds that, to the recipient, they are “I”.

“me” is the source of communication, “you” is the destination of communication; if a computer is communicating, the user is the recipient of the communication so should be called “you”.

Specifically Gmail is the main culprit for this in my life, it lists conversations between “me, Joe”; having “you, Joe” or “Adrian, Joe” would be much better! Gmail even, on the same screen that it lists conversations between “me” and other people, says “You are using 25% of your 7000MB”, so it’s not even consistent!