The transaction pattern and the feature badly missing from exceptions.

Exceptions are the best thing since sliced bread.  If you use them properly, you can write code of much higher quality than without them.  I think of the old days before exceptions, and I wonder how we managed to get anything done back then.  There is, however, one little very important thing missing from implementations of exceptions in all languages that I know of, and it has to do with transactions.

At a high level, exception handling looks structurally similar to transactional processing.  In both cases we have a block of guarded code, during the execution of which we acknowledge the possibility that things may go wrong, in which case we are given the opportunity to leave things exactly as we found them. So, given this similarity, it is no wonder that one can nicely facilitate the other, as this sample code shows:

Bug reporting: a checklist.

Here is a check list for creating useful bug reports:

1. Before reporting, make sure that you are using the latest version of the software.
2. Before reporting something as a bug, make sure it is in fact a bug.
3. Before reporting, play around with the bug to identify it with at least a bit of accuracy.
4. Report through the proper channel, usually an issue tracking system.
5. Make sure that the bug has not already been reported.
6. Invest some time to find a proper title for the bug.
7. State the name of the product in which you found the bug.
8. State the version of the product in which you found the bug.
9. Describe your environment (Operating System name and version, etc)
10. List the steps to reproduce the problem.
11. State the "observed result" of following the steps.
12. State the "expected result" of following the steps.
13. State the reproducibility of the bug. (Or your best estimate of it.)
14. Stick to the facts.
15. Address only one bug per bug report.
16. Include any useful attachments.

Here is a slightly more detailed discussion of each one of the above items:

IntelliJ IDEA feature request: editor actions for moving the caret left & right with Column Selection.

I just submitted a feature request for IntelliJ IDEA.

It can be found here: https://youtrack.jetbrains.com/issue/IDEA-132626

Feature request: editor actions for moving the caret left & right with Column Selection.

It is a fundamental axiom of user interface design that modes kill usability. Having to enter a special mode in order to accomplish something and then having to remember to exit that mode in order to accomplish anything else is bad, bad, bad user interface design, at least when there is even a slight chance that the same thing could be achieved without a special mode. (Think of VI for example: it is the lamest editor ever, and almost all of its lameness is due to the fact that it relies so heavily on modes.)

Unfortunately, programmers tend to think a lot in terms of modes, so the first time the user of an editor asked the programmer of that editor for the ability to do block selection ("column selection" in IntelliJ IDEA parlance) the programmer said "sure, I will add a new mode for this." That's how problems start.

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