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The Apple power brick's metal knob that prevents backwards insertion is my favorite example of poka-yoke. MagSafe is another one, too.
AFAIK the metal knob is the earth connection (which is not used on EU plug, which is very annoying).
I do this all the time for particularly scary yet infrequent scripts that I’m paranoid for accidentally executing. The simpler ones check an environment variable such as RUN_SCARY_THINGY is set to “yes”. The complex ones check that it has a timestamp that is within the past minute. Accidentally run the script without exporting the right var and it prints a message suggesting a cup of coffee.
And I always write the WHERE clause before the DELETE or UPDATE keywords.
The Apple power brick's metal knob that prevents backwards insertion is my favorite example of poka-yoke. MagSafe is another one, too.
You mean the metal knob on the mains side of the power brick? I don't see how the backward insertion of anything would be an issue there. AFAIK the metal knob is the earth connection (which is not used on EU plug, which is very annoying).
Moreover the Europlug has only two pins and fits every socket in Continental Europe, grounded plugs differ by country.
Earlier quoted context omitted.
You mean the metal knob on the mains side of the power brick? I don't see how the backward insertion of anything would be an issue there. AFAIK the metal knob is the earth connection (which is not used on EU plug, which is very annoying).
Why do you find it annoying? Electrical safety norms require either a ground pin attached to the shell or double insulation, and the charger has double insulation. Moreover the Europlug has only two pins and fits every socket in Continental Europe, grounded plugs differ by country.
Though totally safe, the leakage current I feel when touching the metal body is very annoying. See also here: [0]
> Moreover the Europlug has only two pins and fits every socket in Continental Europe, grounded plugs differ by country.
That is correct, hence why the plug in an Apple charger brick is interchangeable. However, the cable attachment is grounded, but the short attachment isn't. When using the cable attachment, the device is grounded and doesn't shock me, with the short attachment I get shocked. Since they did make the grounded cable that fits my countries outlet, it annoys me that I can't get a short grounded attachment with the same plug.
[0] https://superuser.com/questions/1331984/why-does-my-macbook-...
One of my favorite examples is the control lock on some light aircraft. Aircraft are often parked outside and in windy conditions, you want to prevent the control surfaces from being banged around, so you put in control locks. You also don’t want aircraft trying to take off with locked controls (such as the G-IV mishap at Bedford* a few years ago). Enter the control lock that blocks the starter: https://www.csobeech.…
I'm an industrial engineer, so this is all right up my alley! My favorite example is a two-part foam injection machine. They needed to change the injection head, and accidentally put it on backwards. The parts mixed and worked their way back in the supply lines, solidifying along the way. Hundreds of thousands of dollars in lost productivity, multiple weeks to get it fixed. They promptly switched the coupling so it w…
The Genesis sample-return capsule crash-landed due to the accelerometer controlling the parachute deployment being installed upside-down: https://en.wikipedia.org/wiki/Genesis_(spacecraft)#Mishap_In...
I do this all the time for particularly scary yet infrequent scripts that I’m paranoid for accidentally executing. The simpler ones check an environment variable such as RUN_SCARY_THINGY is set to “yes”. The complex ones check that it has a timestamp that is within the past minute. Accidentally run the script without exporting the right var and it prints a message suggesting a cup of coffee.
When writing and running SQL one-offs interactively, I will surround it with `if 1 1 begin end` or comments, or add syntax errors at the top so that I won't accidentally run it without first selecting the part I want to run. I should get into the habit of writing `begin; rollback` instead for extra-safety. And I always write the WHERE clause before the DELETE or UPDATE keywords.
I sometimes get nervous typing 'rm -r' commands, since it starts with a very broad path, and only narrows-down as we type more, e.g. if we hit enter prematurely when typing 'rm -r ~/Downloads/archive.zip' we might delete our entire home directory, or all of our downloads.
For this reason I often prefix dangerous steps with 'echo'; once I'm confident it's correct, I'll then run the script and double-check that variables/flags/etc. expanded as expected; and only then will I remove the echoes.
Slightly different to what is described here, but one of my pet peeves is the "nuclear button" features that devs put in their software - ie easy to activate features that add marginal utility to specific niche workflows but cause irreversible damage to everyone else. Firefox deleting every single one of your pinned tabs on close if you have a second window open is an example of this, as is YouTube jumping to a diffe…
More people need to know about this. Every time I ask some software dev if he knows the term Poka Yoke the answer is always no. Same goes for many operations engineers. And when explained what it is, people assume it is the same as "idiot proof". No, it is not. Is a microwave door that turns the thing off when opened made for idiots? No, just regular people who want to use the microwave without frying their brain in…
One of my favorite examples is the control lock on some light aircraft. Aircraft are often parked outside and in windy conditions, you want to prevent the control surfaces from being banged around, so you put in control locks. You also don’t want aircraft trying to take off with locked controls (such as the G-IV mishap at Bedford* a few years ago). Enter the control lock that blocks the starter: https://www.csobeech.…