It's a Date

It felt like I'd been working on the spreadsheet for a long time but when Excel crashed and then, on recovery, told me I'd last saved it on New Year's Day 1601 I had to wonder whether it was right. But only for a millisecond because, in fact, I'm an inveterate frequent saver. My fingers have been burned so much over the years by losing data due to crash, keyboard shortcut misadventure, server timeout, accidental browser closure and so on that I'm typing this with blackened stumps.

More interesting to me was that it looked like the Windows epoch time was 1601-01-01T01:00 unlike Unix and Linux which use 1970-01-01T00:00. (Repeat after me: ISO date is great, even if it has its own effective epoch, um, mate.)

So I poked around a bit and found that not only is this the Windows epoch date with some justifications of varying believability but that Excel 97 formats had their own built-in epoch time, or times:

Both 1900 and 1904 file types are commonly found in the wild, usually depending on whether the file originated on Windows or Mac. Converting from one to another silently can cause data integrity errors, so Excel won’t change the file type for you. To parse Excel files you have to handle both. That’s not just a matter of loading this bit from the file. It means you have to rewrite all of your date display and parsing code to handle both epochs.

I had planned to write more but I realise I can summarise the remainder in one word: Sigh.

Comments

Ian Taylor said…

The history behind the "1900 on Windows" but "1904 on Macintosh" feature of Excel (http://support.microsoft.com/kb/180162) is a classic example of early (seemingly trivial) design decisions escalating into nightmares down the line.

In fact, the problem goes back beyond what the Microsoft Support page indicates. It originates in a bad date library implementation in early Macintosh software that didn't handle the old "centuries except 400-years are NOT leap years" rule. To get around it, they made dates before 1904 "unsupported".

PS. Repeat after me: ISO dates are better, but NOT as good as they should be.

July 26, 2013 at 10:03 AM

Meet Me Halfway?

The Association for Software Testing is crowd-sourcing a book, Navigating the World as a Context-Driven Tester , which aims to provide responses to common questions and statements about testing from a context-driven perspective . It's being edited by Lee Hawkins who is posing questions on Twitter , LinkedIn , Mastodon , Slack , and the AST mailing list and then collating the replies, focusing on practice over theory. I've decided to contribute by answering briefly, and without a lot of editing or crafting, by imagining that I'm speaking to someone in software development who's acting in good faith, cares about their work and mine, but doesn't have much visibility of what testing can be. Perhaps you'd like to join me? --00-- "Stop answering my questions with questions." Sure, I can do that. In return, please stop asking me questions so open to interpretation that any answ...

The Best Programmer Dan Knows

I was pairing with my friend Vernon at work last week, on a tool I've been developing. He was smiling broadly as I talked him through what I'd done because we've been here before. The tool facilitates a task that's time-consuming, inefficient, error-prone, tiresome, and important to get right. Vern knows that those kinds of factors trigger me to change or build something, and that's why he was struggling not to laugh out loud. He held himself together and asked a bunch of sensible questions about the need, the desired outcome, and the approach I'd taken. Then he mentioned a talk by Daniel Terhorst-North, called The Best Programmer I Know, and said that much of it paralleled what he sees me doing. It was my turn to laugh then, because I am not a good programmer, and I thought he knew that already. What I do accept, though, is that I am focussed on the value that programs can give, and getting some of that value as early as possible. He sent me a link to the ta...

Can Code, Can't Code, Is Useful

The Association for Software Testing is crowd-sourcing a book, Navigating the World as a Context-Driven Tester , which aims to provide responses to common questions and statements about testing from a context-driven perspective . It's being edited by Lee Hawkins who is posing questions on Twitter , LinkedIn , Mastodon , Slack , and the AST mailing list and then collating the replies, focusing on practice over theory. I've decided to contribute by answering briefly, and without a lot of editing or crafting, by imagining that I'm speaking to someone in software development who's acting in good faith, cares about their work and mine, but doesn't have much visibility of what testing can be. Perhaps you'd like to join me? --00-- "If testers can’t code, they’re of no use to us" My first reaction is to wonder what you expect from your testers. I am immediately interested ...

Beginning Sketchnoting

In September 2017 I attended Ian Johnson 's visual note-taking workshop at DDD East Anglia . For the rest of the day I made sketchnotes, including during Karo Stoltzenburg 's talk on exploratory testing for developers (sketch below), and since then I've been doing it on a regular basis. Karo recently asked whether I'd do a Team Eating (the Linguamatics brown bag lunch thing) on sketchnoting. I did, and this post captures some of what I said. Beginning sketchnoting, then. There's two sides to that: I still regard myself as a beginner at it, and today I'll give you some encouragement and some tips based on my experience, to begin sketchnoting for yourselves. I spend an enormous amount of time in situations where I find it helpful to take notes: testing, talking to colleagues about a problem, reading, 1-1 meetings, project meetings, workshops, conferences, and, and, and, and I could go on. I've long been interested in the approaches I've evol...

Don't Know? Find Out!

In What We Know We Don't Know , Hillel Wayne crisply summarises a handful of research findings about software development, describes how the research is carried out and reviewed and how he explores it, and contrasts those evidence-based results with the pronouncements of charismatic thought leaders. He also notes how and why this kind of research is hard in the software world. I won't pull much from the talk because I want to encourage you to watch it. Go on, it's reasonably short, it's comprehensible for me at 1.25x, and you can skip the section on Domain-Driven Design (the talk was at DDD Europe) if that's not your bag. Let me just give the same example that he opens with: research shows that most code reviews focus more on the first file presented to reviewers rather than the most important file in the eye of the developer. What we should learn: flag the starting and other critical files to receive more productive reviews. You never even thought about that possi...

How do I Test AI?

Recently a few people have asked me how I test AI. I'm happy to share my experiences, but I frame the question more broadly, perhaps something like this: what kinds of things do I consider when testing systems with artificial intelligence components . I freestyled liberally the first time I answered but when the question came up again I thought I'd write a few bullets to help me remember key things. This post is the latest iteration of that list. Caveats: I'm not an expert; what you see below is a reminder of things to pick up on during conversations so it's quite minimal; it's also messy; it's absolutely not a guide or a set of best practices; each point should be applied in context; the categories are very rough; it's certainly not complete. Also note that I work with teams who really know what they're doing on the domain, tech, and medical safety fronts and some of the things listed here are things they'd typically do some or all of. Testing ...

Express, Listen, and Field

Last weekend I participated in the LLandegfan Exploratory Workshop on Testing (LLEWT) 2024, a peer conference in a small parish hall on Anglesey, north Wales. The topic was communication and I shared my sketchnotes and a mind map from the day a few days ago. This post summarises my experience report. Express, Listen, and Field Just about the most hands-on, practical, and valuable training I have ever done was on assertiveness with a local Cambridge coach, Laura Dain . In it she introduced Express, Listen, and Field (ELF), distilled from her experience across many years in the women’s movement, business, and academia. ELF: say your key message clearly and calmly, actively listen to the response, and then focus only on what is relevant to your needs. I blogged a little about it back in 2017 and I've been using it ever since. Assertiveness In a previous role, I was the manager of a test team and organised training for the whole ...

Software Sisyphus

The Association for Software Testing is crowd-sourcing a book, Navigating the World as a Context-Driven Tester , which aims to provide responses to common questions and statements about testing from a context-driven perspective . It's being edited by Lee Hawkins who is posing questions on Twitter , LinkedIn , Mastodon , Slack , and the AST mailing list and then collating the replies, focusing on practice over theory. I've decided to contribute by answering briefly, and without a lot of editing or crafting, by imagining that I'm speaking to someone in software development who's acting in good faith, cares about their work and mine, but doesn't have much visibility of what testing can be. Perhaps you'd like to join me? --00-- "How can I possibly test 'all the stuff' every iteration?" Whoa! There's a lot to unpack there, so let me break it down a little: who is suggesting that "al...

Not a Happy Place

A few months ago I stopped having therapy because I felt I had stabilised myself enough to navigate life without it. For the time being, anyway. I'm sure the counselling helped me but I couldn't tell you how and I've chosen not to look deeply into it. For someone who is usually pretty analytical this is perhaps an interesting decision but I knew that I didn't want to be second-guessing my counsellor, Sue, or mentally cross-referencing stuff that I'd researched while we were talking. And talk was what we mostly did, with Sue suggesting hardly any specific tools for me to try. One that she did recommend was finding a happy place to visualise, somewhere that I could be out of the moment for a moment to calm disruptive thoughts. (Something like this .) Surprisingly, I found that I couldn't conjure anywhere up inside my head. That's when I realised that I've always had difficulty seeing with my mind's eye but never called it out. If I try to imagine ev...

Why Question?

Questions are a powerful testing tool and, like any tool, can be used in different ways in different scenarios with different motivations and different results. A significant part of my role is generating questions and I will generally have a lot of them. I will rarely ask them all, though, and I've put a lot of time and effort into learning to be comfortable with that. A couple of examples: I was in a meeting this week where the technical conversation was too deep for me to give a perspective from a position of knowledge. I could have disengaged, but I didn't. Instead, I asked occasional questions, not wanting to derail the discussion or disrupt the flow. Some were detail questions, to help grow my understanding. Some were scoping questions, to help understand motivations. The one that really landed, however, was about the focus of the meeting. Although I couldn't contribute at a low level, I understood enough to suspect that we were not discussing the key problem tha...

Hiccupps

Search This Blog