More from Ognjen Regoje • ognjen.io
From the links in the sources, the following code snippet can be used to track the cursor: <style> .dot { background: red; position: absolute; width: 2px; height: 2px; z-index: 10000; } </style> (function () { "use strict"; document.onmousemove = handleMouseMove; function handleMouseMove(event) { var dot, eventDoc, doc, body, pageX, pageY; event = event || window.event; // IE-ism // If pageX/Y aren't available and clientX/Y // are, calculate pageX/Y - logic taken from jQuery // Calculate pageX/Y if missing and clientX/Y available if (event.pageX == null && event.clientX != null) { eventDoc = (event.target && event.target.ownerDocument) || document; doc = eventDoc.documentElement; body = eventDoc.body; event.pageX = event.clientX + ((doc && doc.scrollLeft) || (body && body.scrollLeft) || 0) - ((doc && doc.clientLeft) || (body && body.clientLeft) || 0); event.pageY = event.clientY + ((doc && doc.scrollTop) || (body && body.scrollTop) || 0) - ((doc && doc.clientTop) || (body && body.clientTop) || 0); } // Add a dot to follow the cursor dot = document.createElement("div"); dot.className = "dot"; dot.style.left = event.pageX + "px"; dot.style.top = event.pageY + "px"; document.body.appendChild(dot); } })(); You can then wrap that into a helper that you can call in your test. You can just page.execute_script(helper_js) and you can inject the CSS similarly. Then binding.pry after that’s done and move the cursor around to get the correct offsets. Note that if you add this javascript snippet hover will no longer trigger on your elements because a new dot element will always be under the cursor. Tracking the cursor in Selenium driven Chrome was originally published by Ognjen Regoje at Ognjen Regoje • ognjen.io on January 27, 2024.
There was a great post about doing unforgettable work. Absolutely. Go above and beyond. Do what’s right. But also, do forgettable work. Work that you won’t remember the following week. Do a lot of it. In fact, do at least 30 minutes of utterly forgettable work on something you’re trying to improve every day. Very soon it’ll stop being forgettable. Do forgettable work was originally published by Ognjen Regoje at Ognjen Regoje • ognjen.io on January 27, 2024.
Over the past year or so I’ve done about two dozen systems design interviews (as an interviewer) and have two somewhat subtle observations that would help some candidates. 1. The word system has two meanings The definition most engineers reach for immediately is the one relating to computers. But the organization itself is a system, in a generic meaning of the word. It’s important to consider the organization for two reasons: 1. Its structure informs the computer systems Boundaries between domains are often strong indicators that boundaries between computer systems should also exist. 2. Tech exists in service of the business And putting systems in the context of the orga demonstrates the understanding that business requirements take precedence over technical convenience. These two considerations get considerably more important with seniority. While junior developers often don’t consider the organization aspect, their area of influence is local so it’s not too relevant to their everyday work. On the other hand, for staff+ engineers who are supposed to influence entire domains or even the whole organization, it’s crucial. 2. The interview is about design Several candidates shy away from designing a system using tech they theoretically know about but wouldn’t be able to implement themselves. It mostly happens to senior engineers who are in a transitionary phase to staff where they have a wide overview of tech and understand much of the implications to the organization. They have an overview of a lot of tech and can discuss tradeoffs. But, they do not have hands-on experience in all of them. The second is that candidates often don’t recognize that design is iterative. As the interview progresses the experienced engineer re-evaluates assumptions, re-checks constraints and iterates on the design. Components can be changed, replaced or removed entirely. The less experienced candidates typically just add components. The third is that design is about trade-offs. What are you willing to sacrifice and most importantly why? And you’re not being evaluated on the final decision but on the process you take to get there. As silly as it sounds, system design interviews are about systems and design was originally published by Ognjen Regoje at Ognjen Regoje • ognjen.io on January 20, 2024.
In a recent conversation with some colleagues, we were talking about how startups make the trade-off between design, domain-driven specifically, in favor of speed. They intentionally take on debt, technical and otherwise, to move faster. I wasn’t in favour of employing DDD in a startup because it’s expensive and slow for a small system. There comes a time when the startup code needs to transition into enterprise DDD-style code, but I think it can be made if and when necessary. After the conversation, I thought about the shortcuts I took building Supplybunny but noticed a few things that I did that were DDD-like. E-commerce as a domain seems to encourage the same practices that DDD advocates for. Ubiquitous language When we started Supplybunny I knew little about the food and beverage industry. That’s what prompted me to learn the jargon. Besides, the different actors used different language. For instance, a supplier would call a product an “SKU”, while a buyer would call it an “ingredient”. A supplier would care about an order and a logistics partner would care about a delivery or shipment. The difference in language made it plenty clear that there were different contexts at play even if I wasn’t intentionally trying to separate them. Bounded contexts In e-commerce bounded contexts are clearer than in most other domains. There is a public search for which you don’t need to log in. The way a supplier and a buyer interact with orders and the information they need to see is different. On the admin side, different departments need to see different things: logistics don’t care about customer support information, and vice versa. Aggregates A big part of e-commerce is dealing with the financial aspect of it. A key part of that is that the order information must be isolated and not change as a result of changes elsewhere. For instance, the product name in an order item, the supplier address in the invoice, and the delivery charge. Not only that, but several fields have multiple values. Take, for instance, the delivery charge: one amount is shown to the buyer, one to the supplier, one to the admin, and one might be sent to an external provider. And not just that, but each of these must be independently traceable - that is, you must be able to generate an account statement for each of those actors. This naturally encourages duplication and isolation of data. Two patterns I used to manage that were the functional model and the actor model. All these requirements naturally lead to clearer boundaries between contexts. Lessons in DDD from building an e-commerce platform was originally published by Ognjen Regoje at Ognjen Regoje • ognjen.io on January 19, 2024.
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One of my recent home organisation projects has been sorting out my LEGO collection. I have a bunch of sets which are mixed together in one messy box, and I’m trying to separate bricks back into distinct sets. My collection is nowhere near large enough to be worth sorting by individual parts, and I hope that breaking down by set will make it all easier to manage and store. I’ve been creating spreadsheets to track the parts in each set, and count them out as I find them. I briefly hinted at this in my post about looking at images in spreadsheets, where I included a screenshot of one of my inventory spreadsheets: These spreadsheets have been invaluable – I can see exactly what pieces I need, and what pieces I’m missing. Without them, I wouldn’t even attempt this. I’m about to pause this cleanup and work on some other things, but first I wanted to write some notes on how I’m creating these spreadsheets – I’ll probably want them again in the future. Getting a list of parts in a set There are various ways to get a list of parts in a LEGO set: Newer LEGO sets include a list of parts at the back of the printed instructions You can get a list from LEGO-owned website like LEGO.com or BrickLink There are community-maintained databases on sites like Rebrickable I decided to use the community maintained lists from Rebrickable – they seem very accurate in my experience, and you can download daily snapshots of their entire catalog database. The latter is very powerful, because now I can load the database into my tools of choice, and slice and dice the data in fun and interesting ways. Downloading their entire database is less than 15MB – which is to say, two-thirds the size of just opening the LEGO.com homepage. Bargain! Putting Rebrickable data in a SQLite database My tool of choice is SQLite. I slept on this for years, but I’ve come to realise just how powerful and useful it can be. A big part of what made me realise the power of SQLite is seeing Simon Willison’s work with datasette, and some of the cool things he’s built on top of SQLite. Simon also publishes a command-line tool sqlite-utils for manipulating SQLite databases, and that’s what I’ve been using to create my spreadsheets. Here’s my process: Create a Python virtual environment, and install sqlite-utils: python3 -m venv .venv source .venv/bin/activate pip install sqlite-utils At time of writing, the latest version of sqlite-utils is 3.38. Download the Rebrickable database tables I care about, uncompress them, and load them into a SQLite database: curl -O 'https://cdn.rebrickable.com/media/downloads/colors.csv.gz' curl -O 'https://cdn.rebrickable.com/media/downloads/parts.csv.gz' curl -O 'https://cdn.rebrickable.com/media/downloads/inventories.csv.gz' curl -O 'https://cdn.rebrickable.com/media/downloads/inventory_parts.csv.gz' gunzip colors.csv.gz gunzip parts.csv.gz gunzip inventories.csv.gz gunzip inventory_parts.csv.gz sqlite-utils insert lego_parts.db colors colors.csv --csv sqlite-utils insert lego_parts.db parts parts.csv --csv sqlite-utils insert lego_parts.db inventories inventories.csv --csv sqlite-utils insert lego_parts.db inventory_parts inventory_parts.csv --csv The inventory_parts table describes how many of each part there are in a set. “Set S contains 10 of part P in colour C.” The parts and colors table contains detailed information about each part and color. The inventories table matches the official LEGO set numbers to the inventory IDs in Rebrickable’s database. “The set sold by LEGO as 6616-1 has ID 4159 in the inventory table.” Run a SQLite query that gets information from the different tables to tell me about all the parts in a particular set: SELECT ip.img_url, ip.quantity, ip.is_spare, c.name as color, p.name, ip.part_num FROM inventory_parts ip JOIN inventories i ON ip.inventory_id = i.id JOIN parts p ON ip.part_num = p.part_num JOIN colors c ON ip.color_id = c.id WHERE i.set_num = '6616-1'; Or use sqlite-utils to export the query results as a spreadsheet: sqlite-utils lego_parts.db " SELECT ip.img_url, ip.quantity, ip.is_spare, c.name as color, p.name, ip.part_num FROM inventory_parts ip JOIN inventories i ON ip.inventory_id = i.id JOIN parts p ON ip.part_num = p.part_num JOIN colors c ON ip.color_id = c.id WHERE i.set_num = '6616-1';" --csv > 6616-1.csv Here are the first few lines of that CSV: img_url,quantity,is_spare,color,name,part_num https://cdn.rebrickable.com/media/parts/photos/9999/23064-9999-e6da02af-9e23-44cd-a475-16f30db9c527.jpg,1,False,[No Color/Any Color],Sticker Sheet for Set 6616-1,23064 https://cdn.rebrickable.com/media/parts/elements/4523412.jpg,2,False,White,Flag 2 x 2 Square [Thin Clips] with Chequered Print,2335pr0019 https://cdn.rebrickable.com/media/parts/photos/15/2335px13-15-33ae3ea3-9921-45fc-b7f0-0cd40203f749.jpg,2,False,White,Flag 2 x 2 Square [Thin Clips] with Octan Logo Print,2335pr0024 https://cdn.rebrickable.com/media/parts/elements/4141999.jpg,4,False,Green,Tile Special 1 x 2 Grille with Bottom Groove,2412b https://cdn.rebrickable.com/media/parts/elements/4125254.jpg,4,False,Orange,Tile Special 1 x 2 Grille with Bottom Groove,2412b Import that spreadsheet into Google Sheets, then add a couple of columns. I add a column image where every cell has the formula =IMAGE(…) that references the image URL. This gives me an inline image, so I know what that brick looks like. I add a new column quantity I have where every cell starts at 0, which is where I’ll count bricks as I find them. I add a new column remaining to find which counts the difference between quantity and quantity I have. Then I can highlight or filter for rows where this is non-zero, so I can see the bricks I still need to find. If you’re interested, here’s an example spreadsheet that has a clean inventory. It took me a while to refine the SQL query, but now I have it, I can create a new spreadsheet in less than a minute. One of the things I’ve realised over the last year or so is how powerful “get the data into SQLite” can be – it opens the door to all sorts of interesting queries and questions, with a relatively small amount of code required. I’m sure I could write a custom script just for this task, but it wouldn’t be as concise or flexible. [If the formatting of this post looks odd in your feed reader, visit the original article]
For some purpose, the DOGE people are burrowing their way into all US Federal Systems. Their complete control over the Treasury Department is entirely insane. Unless you intend to destroy everything, making arbitrary changes to complex computer systems will result in destruction, even if that was not your intention. No
A lieutenant colonel in the Soviet Air Defense Forces prevented the end of human civilization on September 26th, 1983. His name was Stanislav Petrov. Protocol dictated that the Soviet Union would retaliate against any nuclear strikes sent by the United States. This was a policy of mutually assured destruction, a doctrine that compels a horrifying logical conclusion. The second and third stage effects of this type of exchange would be even more catastrophic. Allies for each side would likely be pulled into the conflict. The resulting nuclear winter was projected to lead to 2 billion deaths due to starvation. This is to say nothing about those who would have been unfortunate enough to have survived. Petrov’s job was to monitor Oko, the computerized warning systems built to centralize Soviet satellite communications. Around midnight, he received a report that one of the satellites had detected the infrared signature of a single launch of a United States ICBM. While Petrov was deciding what to do about this report, the system detected four more incoming missile launches. He had minutes to make a choice about what to do. It is impossible to imagine the amount of pressure placed on him at this moment. Source: Stanislav Petrov, Soviet officer credited with averting nuclear war, dies at 77 by Schwartzreport. Petrov lived in a world of deterministic systems. The technologies that powered these warning systems have outputs that are guaranteed, provided the proper inputs are provided. However, deterministic does not mean infallible. The only reason you are alive and reading this is because Petrov understood that the systems he observed were capable of error. He was suspicious of what he was seeing reported, and chose not to escalate a retaliatory strike. There were two factors guiding his decision: A surprise attack would most likely have used hundreds of missiles, and not just five. The allegedly foolproof Oko system was new and prone to errors. An error in a deterministic system can still lead to expected outputs being generated. For the Oko system, infrared reflections of the sun shining off of the tops of clouds created a false positive that was interpreted as detection of a nuclear launch event. Source: US-K History by Kosmonavtika. The concept of erroneous truth is a deep thing to internalize, as computerized systems are presented as omniscient, indefective, and absolute. Petrov’s rewards for this action were reprimands, reassignment, and denial of promotion. This was likely for embarrassing his superiors by the politically inconvenient shedding of light on issues with the Oko system. A coerced early retirement caused a nervous breakdown, likely him having to grapple with the weight of his decision. It was only in the 1990s—after the fall of the Soviet Union—that his actions were discovered internationally and celebrated. Stanislav Petrov was given the recognition that he deserved, including being honored by the United Nations, awarded the Dresden Peace Prize, featured in a documentary, and being able to visit a Minuteman Missile silo in the United States. On January 31st, 2025, OpenAI struck a deal with the United States government to use its AI product for nuclear weapon security. It is unclear how this technology will be used, where, and to what extent. It is also unclear how OpenAI’s systems function, as they are black box technologies. What is known is that LLM-generated responses—the product OpenAI sells—are non-deterministic. Non-deterministic systems don’t have guaranteed outputs from their inputs. In addition, LLM-based technology hallucinates—it invents content with no self-knowledge that it is a falsehood. Non-deterministic systems that are computerized also have the perception as being authoritative, the same as their deterministic peers. It is not a question of how the output is generated, it is one of the output being perceived to come from a machine. These are terrifying things to know. Consider not only the systems this technology is being applied to, but also the thoughtless speed of their integration. Then consider how we’ve historically been conditioned and rewarded to interpret the output of these systems, and then how we perceive and treat skeptics. We don’t live in a purely deterministic world of technology anymore. Stanislav Petrov died on September 18th, 2017, before this change occurred. I would be incredibly curious to know his thoughts about our current reality, as well as the increasing abdication of human monitoring of automated systems in favor of notably biased, supposed “AI solutions.” In acknowledging Petrov’s skepticism in a time of mania and political instability, we acknowledge a quote from former U.S. Secretary of Defense William J. Perry’s memoir about the incident: [Oko’s false positives] illustrates the immense danger of placing our fate in the hands of automated systems that are susceptible to failure and human beings who are fallible.
In our *Ambsheets* project, we are exploring a small extension to the familiar spreadsheet: **what if a single spreadsheet cell could hold multiple values at once**?
I am not going to repeat the news. But man, things are really, really bad and getting worse in America. It’s all so unendingly stupid and evil. The tech industry is being horrible, too. Wishing strength to the people who are much more exposed to the chaos than I am. Reading A Confederacy of Dunces was such a perfect novel. It was pure escapism, over-the-top comedy, and such an unusual artifact, that was sadly only appreciated posthumously. Very earnestly I believe that despite greater access to power and resources, the box labeled “socially acceptable ways to be a man” is much smaller than the box labeled “socially acceptable ways to be a woman.” This article on the distinction between patriarchy and men was an interesting read. With the whole… politics out there, it’s easy to go off the rails with any discussion about men and women and whether either have it easy or hard. The same author wrote this good article about declining male enrollment in college. I think both are worth a read. Whenever I read this kind of article, I’m reminded of how limited and mostly fortunate my own experience is. There’s a big difference, I think, in how vigorously you have to perform your gender in some red state where everyone owns a pickup truck, versus a major city where the roles are a little more fluid. Plus, I’ve been extremely fortunate to have a lot of friends and genuine open conversations about feelings with other men. I wish that was the norm! On Having a Maximum Wealth was right up my alley. I’m reading another one of the new-French-economist books right now, and am still fascinated by the prospect of wealth taxes. My friend David has started a local newsletter for Richmond, Virginia, and written a good piece about public surveillance. Construction Physics is consistently great, and their investigation of why skyscrapers are all glass boxes is no exception. Watching David Lynch was so great. We watched his film Lost Highway a few days after he passed, and it was even better than I had remembered it. Norm Macdonald’s extremely long jokes on late-night talk shows have been getting me through the days. Listening This song by the The Hard Quartet – a supergroup of Emmett Kelly, Stephen Malkmus (Pavement), Matt Sweeney and Jim White. It’s such a loving, tender bit of nonsense, very golden-age Pavement. They also have this nice chill song: I came across this SML album via Hearing Things, which has been highlighting a lot of good music. Small Medium Large by SML It’s a pretty good time for these independent high-quality art websites. Colossal has done the same for the art world and highlights good new art: I really want to make it out to see the Nick Cave (not the musician) art show while it’s in New York.