Diomidis Spinellis
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coolsweng.bsky.social
Diomidis Spinellis
@coolsweng.bsky.social
700 followers 100 following 66 posts
Professor of software engineering at AUEB and software analytics at TU Delft, programmer, technology author. https://www.spinellis.gr/
(Tech tweets here. Follow @DSpinellis for Greek/Greece tweets.)
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coolsweng.bsky.social
I just received an AI-generated GitHub pull-request that incorrectly replaced 450 test code lines with a comment. Be VERY CAREFUL when reviewing out-of-the-blue PRs these days. AI-generated ones are likely to contain difficult-to-spot faults hidden as plausible fixes.

github.com/dspinellis/g...
PR diff
November 7, 2025 at 9:46 AM
coolsweng.bsky.social
Στις 5 Νοεμβρίου λήγει η διορία της διαδικασίας έκδοσης του Προσωπικού Αριθμού.Με τη γεννήτρια γραμμάτων προσωπικού αριθμού μπορείτε να επιλέξετε εσείς έναν καλό συνδυασμό γραμμάτων για τον προσωπικό σας αριθμό. Θα τη βρείτε στο www.balab.aueb.gr/genpa/
November 1, 2025 at 8:17 PM
coolsweng.bsky.social
I just added a note in the advice for writing LaTeX documents GitHub repository to avoid using the “itemize” environment, when you're describing elements. The “description” environment is better for this purpose.

github.com/dspinellis/l...
October 27, 2025 at 11:58 AM
coolsweng.bsky.social
Fun, fun, fun! I'm running a binary tournament merge to combine 64 SQLite databases (83 GB in total) into one. More details in doi.org/10.1109/MS.2...
Process tree output.
October 18, 2025 at 11:27 AM
coolsweng.bsky.social
With all the GenAI buzz we tend to forget the value of 100% correct deterministic tools. Thank you Rust clippy!
Checking uu_sed v0.0.1 (/xfs/dds/sed/src/uu/sed) error: manual implementation of `.is_multiple_of()` --> src/uu/sed/src/fast_io.rs:869:8 | 869 | if (out_off + head_align) % block_size != 0 { | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `!(out_off + head_align).is_multiple_of(block_size)` | = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#manual_is_multiple_of = note: `-D clippy::manual-is-multiple-of` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(clippy::manual_is_multiple_of)]`
September 19, 2025 at 5:35 PM
coolsweng.bsky.social
Google Scholar's lack of an API hinders automation and scientometric studies. In common with all proprietary academic databases, searches are opaque and non-replicable. With the Alexandria3k Python package you can run sophisticated queries on your laptop. dspinellis.github.io/alexandria3k/
Logos of Crossref, DataCire, ORCID, ROR, PubMed, USPTO
August 27, 2025 at 7:39 AM
coolsweng.bsky.social
That's a first! As I write a program's error message, I catch myself thinking whether GenAI will be able to understand it and produce a useful suggestion. (It does.)
That message means your script `fetch-uspto.sh` is expecting an environment variable named **`MYODP_KEY`**, which hasn’t been set in your shell. This usually happens when a script needs an API key to authenticate against the USPTO Open Data Portal (ODP). To fix it, you need to: 1. **Obtain the API key** * Go to the [USPTO Open Data Portal](https://developer.uspto.gov/data/bulk-search) and sign in (or register). * Generate an API key. 2. **Set the environment variable** before running the script: ```bash export MYODP_KEY="your_api_key_here" ./fetch-uspto.sh ``` Or prepend it inline: ```bash MYODP_KEY="your_api_key_here" ./fetch-uspto.sh ``` 3. If you want it to persist across sessions, add the line to your shell config (e.g., `~/.bashrc`, `~/.zshrc`): ```bash export MYODP_KEY="your_api_key_here" ``` --- Do you want me to show you how to modify `fetch-uspto.sh` so that it gives clearer instructions (like printing how to set the variable), instead of just failing?
August 24, 2025 at 3:56 PM
coolsweng.bsky.social
Many years ago I contributed to #GraphViz code for several new node shapes, including UML notes. Now #ChatGPT advises me how to use them! 😃
— In UML create a comment note. — In UML diagrams, a **comment** (or “note”) is shown as a rectangle with a dog-eared corner. Graphviz can mimic this by using `shape=note`. Example in DOT: ```dot digraph UML_Comment { rankdir=LR; node [fontname="Arial", fontsize=12]; // Regular UML component A [label="«component»\nOrder Service", shape=component]; // UML comment Cmt [label="Processes orders\nand handles payments", shape=note, style=filled, fillcolor="#ffffcc"]; // Dashed association from comment to element Cmt -> A [style=dashed, arrowhead=none]; } ``` **Key points:** * `shape=note` → dog-eared corner rectangle. * `fillcolor` → makes the note background match UML style (light yellow is common). * `style=dashed, arrowhead=none` → matches UML’s “annotates” relationship from a comment to a model element. --- If you want, I can insert UML comment nodes into your **O1/O2 Graphviz diagram** to annotate entire clusters or specific tasks, so they look like sticky notes connected to the relevant part. Would you like me to do that?
August 14, 2025 at 10:28 AM
coolsweng.bsky.social
I'm sure psychologists have a diagnostic name for this disorder.
August 7, 2025 at 11:32 AM
coolsweng.bsky.social
Ever wondered why car ergonomics have gone down the drain as touch screens replaced buttons to drive down costs? This reader comment on an @financialtimes.com article on the topic says it all.
Please use the sharing tools found via the share button at the top or side of articles. Copying articles to share with others is a breach of FT.com T&Cs and Copyright Policy. Email licensing@ft.com to buy additional rights. Subscribers may share up to 10 or 20 articles per month using the gift article service. More information can be found at https://www.ft.com/tour. https://www.ft.com/content/b46311ba-a5a1-4754-8d40-eaae475f01eb I’m an industrial designer and I used to work in the design department at a major car manufacturer. I’m a petrol head, and have been my whole life. By now, I’ve probably driven over a hundred different vehicles across various generations of interface technology. Here’s the thing: the user experience designers in my team — the ones tasked with designing the digital interfaces now frequently deployed and rightly deplored in this article — had little-to-no interest in cars. In many cases, they were only working for a car maker because they couldn’t get the jobs they really wanted in tech companies. But the kicker was that many of them didn’t have drivers’ licenses, let alone any interest in how cars really work. All they saw was a screen, abstracted from the broader reality of operating a 2-tonne projectile in a world of sometimes moving, sometimes fleshy, and sometimes immovable targets.
July 9, 2025 at 11:02 AM
coolsweng.bsky.social
My LLM coding interactions taught me that their benchmark results vastly overstate their capabilities. The paper by M. Mancoridis et al. “Potemkin Understanding in LLMs” explains and formalizes my feeling. Benchmarks derived from human tests are unsuitable for LLM assessment. doi.org/10.48550/arX...
June 27, 2025 at 6:12 PM
coolsweng.bsky.social
This week two US courts ruled in favor of AI's use of copyrighted works to train LLMs. How is such a use legal? Should it be legal? Two questions with very different answers. More (and an explanation of the audio cassette's relevance) at www.spinellis.gr/blog/20250626/
A Sony compact cassette. https://en.wikipedia.org/wiki/Cassette_(format)#/media/File:Sony_C60_Low_Noise_Compact_Cassettte.jpg by Mikus
June 26, 2025 at 11:50 AM
coolsweng.bsky.social
Wow! The Rust compiler correctly guessed the correct method I should be calling. Helpful and very impressive error handling!
May 29, 2025 at 5:57 PM
coolsweng.bsky.social
In 2023 a fake AI-generated scientific article was falsely attributed to me. I was not the scheme's only victim. My study, just published in the Research Integrity and Peer Review journal, analyzes what going on and who profited from the mass publication of AI-generated articles. rdcu.be/enQqG
Falsely attributed AI-generated article Title and abstract page: False authorship: an explorative case study around an AI-generated article published under my name
May 27, 2025 at 2:44 PM
coolsweng.bsky.social
When you forget to switch the active window from ChatGPT to vim…
1gt307G
May 8, 2025 at 6:27 PM
coolsweng.bsky.social
Shocking! When I said text should wrap at 72 columns, a student asked what a “column” is. With punched cards and fixed-width font line / dot matrix printers fading into history, the idea of a text column doesn't seem to be obvious anymore.
May 2, 2025 at 8:45 PM
coolsweng.bsky.social
ChatGPT seems to struggle with its "Deep research" feature due to difficulties in accessing several web sites. I guess the high-volume of its accesses is causing many sites to block it. These examples are from a single prompt.
April 25, 2025 at 7:00 AM
coolsweng.bsky.social
Correct, but verbose and unreadable ChatGPT (4o) code (in red) vs the human-edited equivalent (in green). (The hex_digits string isn't even used.) Without human code ownership our software risks degenerating into unmaintainable junk.
- // Check four hex digits (must be 0-9 or A-F) - char h3 = input[i+3], h4 = input[i+4], h5 = input[i+5], h6 = input[i+6]; - if (((h3 >= '0' && h3 <= '9') || (h3 >= 'A' && h3 <= 'F')) && - ((h4 >= '0' && h4 <= '9') || (h4 >= 'A' && h4 <= 'F')) && - ((h5 >= '0' && h5 <= '9') || (h5 >= 'A' && h5 <= 'F')) && - ((h6 >= '0' && h6 <= '9') || (h6 >= 'A' && h6 <= 'F'))) { + if (isxdigit(input[i + 3]) + && isxdigit(input[i + 4]) + && isxdigit(input[i + 5]) + && isxdigit(input[i + 6])) { + static char hexstr[5]; + memcpy(hexstr, input + i + 3, 4); // Parse the 4-digit hex code point - unsigned int codepoint = 0; - const char *hex_digits = "0123456789ABCDEF"; - for (int j = 3; j < 7; ++j) { - codepoint <<= 4; - char c = input[i+j]; - if (c >= '0' && c <= '9') { - codepoint |= (unsigned int)(c - '0'); - } else { - codepoint |= (unsigned int)((c - 'A') + 10); - } - } + unsigned int codepoint = (unsigned int)strtoul(hexstr, NULL, 16);
April 23, 2025 at 3:12 PM
coolsweng.bsky.social
Many sites provide incorrect or incomplete BibTeX entries. I therefore just use the provided DOI and a small shell script to create the BibTeX from it from the definitive data retrieved from Crossref.
April 14, 2025 at 7:03 AM
coolsweng.bsky.social
Can you spot the six errors in this completely bogus GenAI-derived diagram? Read more in my blog entry on the perils of GenAI student submissions.

www.spinellis.gr/blog/20250408/
Bogus GenAI diagram
April 11, 2025 at 6:56 AM
coolsweng.bsky.social
In the past I've had Google Search, Wikipedia, and StackOverflow point me to my own material for answers. Now ChatGPT does the same.
ChatGPT recommends material from my own web site.
April 4, 2025 at 5:52 PM
coolsweng.bsky.social
As I was watching the Sun within the clouds, I noticed that a part was missing. Through a quick web search I found out I was watching a partial solar eclipse! I took the photo with a non-fancy smartphone.
Solar eclipse 2025
March 29, 2025 at 12:37 PM
coolsweng.bsky.social
I love the informative error messages that Clippy provides for Rust programs.
March 22, 2025 at 1:06 PM
coolsweng.bsky.social
When a group of disgruntled academic researchers switches its career to Hollywood…
January 13, 2025 at 8:00 AM
coolsweng.bsky.social
Today, in my Java streams lecture I accompanied a unique words example illustrating their use with a presentation of D. McIlroy's critique of D. Knuth's code in CACM's “Programming Pearls column” and an Indiana Jones scene as a parable.
dl.acm.org/doi/pdf/10.1...
www.youtube.com/watch?v=kQKr...
Files .lines(Paths.get(args[0])) .flatMap(line -> Stream.of(line.split("\\W+"))) .sorted() .distinct() .filter((x) -> x.length() > 0) .forEach(System.out::println);
January 8, 2025 at 7:10 PM