Bret Victor - Inventing on Principle

Interestingly enough, in his code snippets he is using JavaScript, whereas one of my personal guiding principles is thou shalt not suffer an error to go undetected, which means that no scripting language should be used under any circumstances, for anything at all, by anyone, anywhere, ever. But I digress. Excellent presentation.

Bathyscaphe

The Bathyscaphe logo, a line drawing of bathyscaphe Trieste

by Mike Nakis, based on art found at bertrandpiccard.com

Abstract

This article introduces Bathyscaphe, an open-source java library that you can use to assert that your objects are immutable and/or thread-safe.

The problem

Programmers all over the world are embracing immutability more and more; however, mutation is still a thing, and in all likelihood will continue being a thing for as long as there will be programmers. In a world where both mutable and immutable objects exist side by side, there is often a need to ascertain that an object is of the immutable variety before proceeding to use it for certain purposes. For example, when an object is used as a key in a hash map, it better be immutable, or else the hash code of the key may change, causing the map to severely malfunction.

Furthermore, when an object is not immutable, there is often the need to ascertain that it is at least thread-safe before sharing it between threads, otherwise there will be race conditions, with catastrophic results.

Note that when any of the above goes wrong, it tends to be a bug which is very difficult to troubleshoot.

Fixing broken module names in IntellijIdea

Quite often, when I rename a maven module, IntellijIdea gets confused and keeps showing the old module name in the project view.

• Re-importing maven projects does not help.
• Clearing the IntellijIdea caches and restarting does not help.
• Even deleting the .idea directory does not help.

I discovered that this is happening because: 

• IntellijIdea keeps information about a project outside of the .idea directory
• IntellijIdea fails to delete that information when you invalidate caches and restart.

The solution I have found to this problem is:

1. Exit IntellijIdea.
2. Go to the application data directory of IntellijIdea (on my Windows machine, this currently is %USERPROFILE%\AppData\Local\JetBrains\IdeaIC2022.1)
3. Delete the `external_build_system` subdirectory
4. Start IntellijIdea.
5. Re-import all maven projects.

Update:

Shortly after I discovered this, a new release of IntelliJ IDEA came out, (IdeaIC2021.3) and there appears to be no "external_build_system" subdirectory in its directory. Miraculously, it makes use of the "external_build_system" subdirectory of the IdeaIC2021.1 directory!

Also, with this new version, when I apply the above steps, IntellijIdea for some reason starts to believe that I have chosen to "ignore" all of my pom.xml files.  So, I have to open up maven settings, go to "Ignored Files", and uncheck every single one of my pom.xml files.

Mouse Wheel Natural Scrolling in Windows

Some time ago and for about a year I used a Mac, which had natural scrolling by default. I decided to resist the urge to immediately configure it to work like Windows, and instead I made it a point to give natural scrolling a try for at least a while before making up my mind as to whether to keep it or lose it. While giving it a try, I was surprised to see that it was very easy for me to adjust to it, despite the fact that I have been using the unnatural Windows scrolling mode for nearly 30 years. (Ever since the mouse wheel became a thing.) I found that natural scrolling was indeed... natural. So, I kept using it, and I became addicted to it. Ever since then, I always have to configure natural scrolling on any Windows machine that I get my hands on before I can start using that machine.

Artwork based on original mouse-15887 by Arkthus from the Noun Project

Windows is so poor that it does not offer any user interface through which a novice user can change the mouse wheel scrolling mode. To do that you have to edit the registry, and the setting you are going to be modifying is a machine setting, so you will be affecting the mouse wheel mode for all users, not just for yourself. This is unbelievably lame, but hey, that's Windows, we are totally used to lame.

Getting AntiVirus software to trust a Windows Application

From vecteezy.com (Glass Shield Anti-Virus)

One of our customers tried installing our Windows Application on one of their computers and their antivirus software complained. They in turn complained to us, so we had to find a solution. I am documenting the solution here.

Digital Audio Waveform Generation

For various projects of mine I need to be able to synthesize sound, so I decided to take a quick dabble in the realm of Digital Signal Processing. I mean, how hard could it be, right? 

After some fooling around with the Sampled Audio Subsystem of the Java Virtual Machine I was able to hear sinusoidal waveforms of various frequencies from my speakers, and I was starting to think that I am probably almost done, until I tried to play square waveforms. That's when I realized that I had barely scratched the surface. The square waveforms sounded pretty awful at any frequency, and especially at high octaves they sounded like random notes. Triangular waveforms, sawtooth waveforms, really anything except sinusoidal waveforms all suffered from the same problem.

A bit of googling around soon revealed the name of the source of my troubles: aliasing.

A naïvely sampled square wave, exhibiting a bad case of aliasing. Note how some of the peaks and valleys consist of 3 samples, while some consist of only 2 samples.

White-Box vs. Black-Box Testing

I have something blasphemous to tell you.

Unit Testing is wrong.

There, I said it.

I know I just insulted most people's sacred cow.

Sorry, not sorry.

I will explain, bear with me.

What is wrong with Full Stack Development

Inntel Hotel at Amsterdam, Zaandam

Table of Contents

• What is full-stack development

• Why is full-stack development necessary today

• What is wrong with full-stack development

• Conclusion

What is full-stack development

The predominant web application development model today requires splitting application logic in two parts:

• The front-end, running on the browser.
• The back-end, running on the server.

The front-end is typically written in JavaScript, while the back-end is typically written in Java, Scala, C#, or some other programming language. The two ends invariably communicate with each other via REST. The choice of JavaScript and REST is not due to any technical merit inherent in these technologies, (there is none,) but purely due to historical accident; see michael.gr - The Wild, Wild Web.

A web application developer can either focus on one part of the stack, or work on both parts. Due to reasons that will be explained further down, more often than not, web developers are asked to work on both parts simultaneously. When this happens, it is known as full-stack development.

For the purposes of this paper, we will call full-stack development not just this mode of work, but also this architectural style as a whole: full-stack development is when application logic must be written both on the server and on the client.

Full-Stack Development is a paradox, since it suggests a way of work which is contrary to what common sense dictates. Common sense calls for specialists each working on their own area of specialization, so one would expect to see different developers focusing on different layers of the stack, and nobody ever attempting something as preposterous as working on all layers simultaneously. However, there is a technological hurdle which renders this necessary today.

Why is full-stack development necessary today

Windows: how to connect/disconnect wi-fi from command-line

(Useful pre-reading: About these papers)

This assumes that you have previously established a wi-fi connection, so windows has created what it calls a "profile".

In short, the commands are:

netsh wlan connect ssid=<ssid> name=<name>

and

netsh wlan disconnect

To obtain ssid and name, use:

netsh wlan show profile

This should display all existing profile names, and by default, the <name> is the same as the <ssid>.

Things can get more complicated if you have multiple wi-fi adapters, or an ssid that differs from the profile name, but the above should cover the general case.

The Stateful Microservice

I did a quick search for the term and did not find anything concrete, so I thought I might as well publicly document my thoughts.

Photo of two elephants friendly interacting with each other, from The Scientific American: Fact or Fiction?: Elephants Never Forget