Why the 'final' (Java) or 'readonly' (C#) keyword is a bad idea

A quick look at the source code that I have written over the past couple of decades in various work projects and hobby projects of mine shows that the percentage of class member variables that I declare as 'final' in Java or as 'readonly' in C# is in excess of 90%. I declare only about 10% of them as non-final. By looking at parameters and locals, a similar ratio seems to apply: their vast majority is effectively final, meaning that even though I do not explicitly declare them as final, the only time I ever write to them is when I initialize them. I would have been declaring them as final, if doing so was not tedious.

My percentages may be higher than the percentages of the average programmer out there, but I shall be bold enough to claim that this is probably because I pay more attention to quality of code than the average programmer out there.

I will even be as bold as to say that the above was an understatement.

In my book, there is a simple rule: if it can be made final, it absolutely ought to be made final. If there is even a remote chance of making it final, that chance should be pursued tenaciously.

To put it in other words, it is my firm conviction that good code uses 'final' a lot, and bad code uses 'final' sparsely.

So, in light of the fact that immutability is a most excellent quality, and the fact that actual usage shows that values in well written code are in fact immutable far more often than not, it seems to me that the 'final' keyword is a bad idea. Not in the sense that things should not be final, of course, but in the sense that 'final' should be the default nature of all values, and therefore unnecessary. A keyword like 'mutable' should be used to explicitly indicate that something is non-final and therefore allowed (and actually expected) to be modified.

I hope one day we will see a language which  implements this realization.

UPDATE 2015-05-15: It turns out that Rust does this with a 'mut' keyword.

Assertions and Testing

So, since we do software testing, we should quit placing assert statements in production code, right? Let me count the ways in which this is wrong:

(TL;DR: skip to the paragraph containing a red sentence and read only that.)

1. Assertions are optional.

Each programming language has its own mechanism for enabling or disabling assertions. In languages like C++ and C# there is a distinction between a release build and a debug build, and assertions are generally only enabled in the debug build. Java has a simpler mechanism: there is only one build, but assertions do not execute unless the -enableassertions (-ea for short) option is specified in the command line which started the virtual machine. Therefore, if someone absolutely cannot stand the idea that assertions may be executing in a production environment, they can simply refrain from supplying the -ea option; problem solved.

My notes on "Spring in Action" (Manning)

My notes on the "Spring in Action" book by Craig Walls and Ryan Breidenbach from Manning Publications Co.

On Electronic Cigarettes

I have been vaping for about two and a half years now, and it has been one of the best things that have ever happened to me.  Here are some of my thoughts on the subject, written in the form of a "how-to" guide. It may change as I gain more knowledge.

Like most people, I started with various odd contraptions of the kind that you receive as presents, and I quickly realized that the way to go is a specific more-or-less-standard type of device which, rather unsurprisingly, is the type of device that you most often see carried by people who have picked up the habit. It consists of a USB-rechargeable battery, a replaceable bit called the vaporizer, and a tank with a mouthpiece.  These parts fit together by screwing one into the other, (the mouthpiece snaps onto the tank,) and the dimensions of all the junctions are standard, so you can replace each part as needed, and you can even mix and match components from different brands, since they adhere to the same standard.

Standard versus non-standard

There exists a variety of other types of devices which either require their own special charger, or they store the fluid in a sponge instead of a tank, or they are different in this or that or the other respect which makes them incompatible with standard components. My experience says that it is best to stay as far away from them as possible. Sure, some of them look sleek and exclusive, but lack of interoperability results in an unreasonably high extra cost, for benefits which are usually only aesthetic. You might even find a one-of-a-kind system for a price which might seem comparable to the cost of a bulky and motley system put together out of standard components, but in reality the one-of-a-kind system is far more expensive, because if one aspect of it turns out to not suit you, or if one part of it gets lost or broken, the entire system must usually be tossed, while with standard components you only replace the part that needs replacement. If, in addition to all this, you consider the fact that certain components of electronic cigarettes (namely, the batteries) are known beforehand to have a limited lifetime, buying a special system which is guaranteed to have to be thrown away after a few months makes no sense at all, in my opinion.

Benchmarking Java 8 lambdas

Now that Java 8 is out, I was toying in my mind with the concept of a new assertion mechanism which uses lambdas. The idea is to have a central assertion method that works as follows: if assertions are enabled, a supplied method gets invoked to evaluate the assertion expression, and if it returns false, then another supplied method gets invoked to throw an exception. If assertions are not enabled, the assertion method returns without invoking the supplied merhod. This would provide more control over whether assertions are enabled or not for individual pieces of code, as well as over the type of exception thrown if the assertion fails. It would also have the nice-to-have side effect of making 100% code coverage achievable, albeit only apparently so.

Naturally, I wondered whether the performance of such a construct would be comparable to the performance of existing constructs, namely, the 'assert expression' construct and the 'if( checking && expression ) throw ...' construct. I was not hoping for equal performance, not even ballpark equal, just within the same order of magnitude.

Well, the result of the benchmark blew my mind.

Congratulations to the guys that made Java 8, because it turns out that all three constructs take roughly the same amount of time to execute!

Here is my code:

What do you need a debugger for?

In my many years of experience in programming I have noticed that there are some programmers who refuse to use a debugger, or try to use the debugger as little as possible, as in, only when they run out of alternative options. They tend to rely solely on the diagnostic log to troubleshoot problems in their code, so their code tends to spew thousands of lines of log entries per second, and they keep trying to divine the causes of exceptions by just looking at post-mortem stack traces.

Quite often these people do not understand what usefulness others find in debuggers.  I once requested the lead developer of a certain shop (Powernet, Athens, Greece, circa 2000) to enable debugging for me on their development web server so that I can run my debugger on the web site that I was developing in that shop, and she asked me "what do you need a debugger for?" Luckily, she proceeded to fulfil my request after a couple of long seconds of me staring blankly at her.

Listen folks, if you want to be called a "programmer" and if you want to be worth the cost of the keyboard you are pounding on, the debugger needs to be your absolute first tool of choice at the slightest need for troubleshooting, not your last tool of choice, not even your second tool of choice. Companies that develop IDEs go through huge pains to provide us with nice sleek and powerful debuggers so that we can do our job better, don't you dare let their efforts go to waste.

A call stack trace in the diagnostic log of your program will tell you which function was called by which function, and that's all.  This is enough in many simple cases, but when things get just slightly complicated, (and they usually do,) it is not enough.  Lacking any additional information, what you end up doing is theorizing about what might have happened instead of looking and seeing what has happened.

Pronouncing the name of your web server

A memo to developers all over the world whose native language is not English:

Sign of the Apache Web Server

Folks, just so that you know, the world famous Apache Software Foundation which lends its name to its world famous Apache Web Server is not pronounced uh-pach;  it is pronounced uh-pach-ee.  The final letter is not a silent "e", it is a loudly and clearly pronounced "e".

There exist two words in English which are spelled "Apache";  one is of French origin, and according to dictionary.com it means "a Parisian gangster, rowdy, or ruffian".  This one does end in a silent "e", but it is not the one that the Apache Software Foundation was named after.  The other word is of Mexican-Spanish origin, it means "a member of an Athabaskan people of the southwestern U.S.", it ends in a definitely non-silent "e", and it is the word you are looking for.

Head over to dictionary.com to check out these two words and click on the little speaker icons to hear their pronunciation: http://dictionary.reference.com/browse/apache

Also, in the Wikipedia article about the Apache Software Foundation (http://en.wikipedia.org/wiki/Apache_Software_Foundation) we read:

The name 'Apache' was chosen from respect for the Native American Apache Nation, well known for their superior skills in warfare strategy and their inexhaustible endurance. It also makes a pun on "a patchy web server"—a server made from a series of patches—but this was not its origin.

And as a side note to fellow USAians: The same applies to the world famous Porsche brand of cars: the final "e" is not silent.  Please quit saying porsh; it is por-sheh.  See: http://youtu.be/4OuPY-1snyw

Picture of Earth from Orbit in Cosmos S01E07

Nowadays the interwebz abounds with beautiful images of our Earth from orbit. Lately I have picked up the habit of trying to figure out what part of our world is visible when I see such an image. It is usually quite a puzzle, since the scale of the picture is not always obvious, parts of it are always obscured by clouds, the North can really be anywhere, and worst of all, countries are not painted with different colours! (Duh!) I am usually successful in this, but today I had a real tough one.

A couple of seconds into Cosmos: S01E07, there is a picture of Earth from orbit. Click on the picture below and see if you can identify the visible land before reading further down.

You might think that it is really obvious, but then try to verify your hypothesis by comparing the picture above against google earth, and whoops, you will see that you were wrong.

So, what's going on?

"By using this site, you agree to the use of cookies."

If you live outside of Europe you might be lucky enough to have no idea what this is all about, but if you live in Europe you are probably sick and tired by now of this message popping up every time you first visit a site:

"This site uses cookies to help deliver services. By using this site, you agree to the use of cookies." [Learn more] [Got it]

The creators of these sites are not to blame for these messages; they are being forced to display them against their will, (and waste money and resources in doing so,) in order to comply with EU regulations. These messages are mandated by law.

I mean, really, how about this:

"This site uses the Helvetica font to help deliver services. By using this site, you agree to the use of Helvetica." [Learn more] [Got it]

Or this:

"This site uses TCP/IP to help deliver services. By using this site, you agree to the use of TCP/IP." [Learn more] [Got it]

All these statements make precisely the same amount of sense: none.

The legislators who came up with the one about cookies are a bunch of technically illiterate ignoramuses who, in a fashion typical of politicians full of shit, have the audacity to be legislating on things they have absolutely no clue about.  They should be removed from office and prohibited from ever holding any job other than milking goats.

Stackoverflow.com question deleted within 2 minutes.

This question was sighted on stackoverflow.com on Thursday, April 30, 2013.  It was deleted within 2 minutes from being posted, but not before I managed to take a screenshot of the summary.

It is funny when you can tell what's wrong with the code by just looking at the summary!