Slashdot Mirror

← Back to Stories (view on slashdot.org)

What is the Best Bug-as-a-Feature?

Posted by Cliff on from the unexpected-benefits dept.

Bat Country wonders: "The workflow system, at the department I develop for, was hand-coded by my predecessor in a rather short amount of time, resulting in somewhat unreadable code with a number of interesting 'features.' When I took over maintenance of the code base, I started patching bugs and cleaning up the code in preparation for a new set of features. After I was done, I got a pile of complaints about features that had disappeared, which turned out to be caused by the bugs in the code. So, that leads me to ask: what is your favorite bug that you either can't live without or makes your life easier?"

14 of 861 comments (clear)

  1. The money lender bug in Taipan by Anonymous Coward · · Score: 5, Interesting
    Great game! Here.

    The guy who wrote the Windows version actually allows you to turn it on! Overpay the money lender and your money grows at 10% a month! The bug was in the original Apple 2 version and then subsequent ports, like the one to Palm, removed it.

  2. "Subscribe to view" pages visible to Googlebot. by Behrooz · · Score: 5, Interesting

    "Subscribe to view" webpages that are still visible to users browsing as GoogleBot.
     
      User agent switcher extension + Browse pretending to be GoogleBot = Annoying "register/pay to see me!" pages go away. I have no idea how many sites it works on now, but I think it still gets into a lot of archived newspaper articles and suchlike.

    --
    "We have to go forth and crush every world view that doesn't believe in tolerance and free speech." - David Brin
    1. Re:"Subscribe to view" pages visible to Googlebot. by apathy+maybe · · Score: 5, Interesting

      Personally I use the modify headers extension to do the same thing. But I have "I am not a Googlebot/2.1", rather then the full Googlebot string. But I sometimes come across pages that say something along the lines of "You appear to be pretending to be a major search engine when you are not", for those pages I change the header to "I DIDN'T CLAIM TO BE A MAJOR FUCKING SEARCH ENGINE".

      Of course, both are examples of why you shouldn't use "User-Agent" to try and detect what browser or bot is using your webpage. The first allows "illegitimate" users access, and the second blocks legitimate users.

      In fact, you shouldn't trust headers for anything unless you have a secure session. To control access to your webpage to robots, use ROBOTS.TXT or a meta tag, and to control access to other users, password protect. But the trouble is that sites are trying to eat their cake (be crawled and indexed) and have it too (control access to ordinary users).

      --
      I wank in the shower.
  3. Skiing in Starsiege: Tribes by Manatra · · Score: 5, Interesting

    For me, the physics bug that enabled "skiing" in Starsiege: Tribes was the best bug as a feature. It's a bug that became a key defining point of the series.

    A description of skiing is here.

  4. Perl versus Python by goombah99 · · Score: 5, Interesting

    Perl is perhaps one large bug that works so well that it's a great feature. For example in perl when you compare two things you get an answer that is stable no matter what the items are. In python you can't and even when you can the answer is not stable. The order of a sorted list can depend on it's orginal ordering! You cant compare floats to Complex numbers but you can compare strings to complex numbers. Sets are grouped by equality not identity so 4.0 and 4 are the same thing for a set. Which one stays and which one get added to the set depends on the ordering of the lists that were put in the set.
    it's nuts. And the origin of the nutty ness is an obsessive desire not to have default behaviours. Whereas perl is all default behaviours. In the end perl does what you really meant, and python does what you told it.

    in case you think I'm python bashing google what python evangelist david mertz says about python warts.

    --
    Some drink at the fountain of knowledge. Others just gargle.
    1. Re:Perl versus Python by Eicosane · · Score: 5, Interesting

      The broke broke piece of crap he is using is found here: http://en.wikipedia.org/wiki/Significant_figures

      The rule in his example is:

      4(1 sig fig) * 1200 (2 sig figs) = 5000 (1 sig fig & rounded up since 4800 is closer to 5000 than 4000)

      4.0(2 sig figs) * 1200 (2 sig figs) = 4800 (2 sig figs)

      As far as software using sig figs, well...if you are using real world measurements, you should be using sig figs. You can not tell from a general ruler if you are at 0.526876". You can tell that you are between 0.5" and 0.6", so you say 0.56" Past two sig figs, you would really be pulling that out of your bum. Therefore in all the calulations that use the 0.56", you can only have a max of two sig figs in the result. Anything more would rely on you knowing up to say 3+ sig figs in all the numbers used to get the result.

      Point: The number of sig figs you have makes a difference in your result. Sig figs are generally used with real world measurement systems. Computer calculations may not fall into this category, but it would depend.

  5. Nameless Firefox Bookmarks by Headcase88 · · Score: 5, Interesting

    This barely qualifies as bug, more on an inconsistency, but...

    In Firefox, when you make a new bookmark, you need to give it a name. FF grays-out the OK button until you do. This implies that bookmarks weren't meant to be nameless. Here's the "bug": if you go to rename the bookmark, you can make it blank and the OK button remains active.

    So what good is a nameless bookmark? I place all of my frequently-visited bookmarks on the menu bar, to the right of the menus (it's normally wasted space). I have over 25 bookmarks marks there, and if they had names (even one-letter names), they wouldn't fit by a long-shot. The favicons are all I need, so this ability is pretty helpful, and isn't likely to be fixed.

    --
    "When the atomic bomb goes off there's devastation...but when the atomic bong goes off there's celebraaaaation!"
  6. VW close the sunroof bug by Ancient_Hacker · · Score: 5, Interesting

    There were two oversights in the older VW's electrical system:

    (1) You needed the key to close the sunroof.

    (2) But.. a sneak path in the headlight wiring meant you could instead just turn on the headlights and pull on the high-beam flasher (on the turn-signal lever). Enough electricity would flow backwards through the sneak path to operate the sunroof motor. ... ooops, that's more hardware than software. sorry.

  7. telnet -l "-froot" by mmell · · Score: 5, Interesting
    More than once, I've rescued SUN servers where somebody hosed up PAM (or even /etc/passwd /etc/shadow) by breaking in this way.

    A related "bug" is the ability to boot Linux "fail safe" with the notation 'initrd=/bin/sh' on the boot line. As MVS would say, "Thou art God!"

  8. Quake2 strafe jumping by pak9rabid · · Score: 5, Interesting

    I'd have to go with strafe jumping in Quake2. What better way to get the 100 health pack in q2dm1 w/out having to sacrifice precious life w/a rocket jump. w00t!

  9. I dunno by Chris+Burke · · Score: 5, Interesting

    In high school I wrote a program for a physics project that showed electromagnetic wave propagation and interference. Nothing that special, the end result was basically a pretty screensaver with some relevence to physics. In light of that, one of the features I added was a pull-down menu for selecting what color you wanted to use. This was back in the VGA days with a 256 color pallette and manually poking the VGA frame buffer. Due to an off-by-one error in calculating the bounding box of the pull down menu, it was possible to select an invalid index for the color, so instead of selecting a row of the pallette with my nice color gradients set up, it was one of basically random colors. The result was really trippy, so when I discovered the bug, I decided to leave it in. At the open house where my program was running through a projector some bystander discovered the bug and thought it was indeed cool and trippy.

    That's about it. Most of my bugs just break shit. :)

    --

    The enemies of Democracy are
    1. Re:I dunno by DedWisdom · · Score: 5, Interesting

      I had a similar experience when I was younger. I was learning C++ graphics programing on windows (95), and I was trying to simply make a static screen that showed a monochrome random gradient. Well I had some bug in my algorithm, and the screen went crazy, showing this massive arch with these beautiful repeating patterns within the arc, but random static outside of the arc. Okay, weird, changed some +s and some -s, and got it working, fine.

      Years later I started learning about chaos theory and fractals, and something in my head clicked. I instantly had a vivid memory of that bugged screen and realized that it was a fractal. I had accidentally created a rather complex fractal. Blew my mind clean up.

  10. Date library by isj · · Score: 5, Interesting

    Not me, but one of my colleagues took over maintenance of a system which included a date library. The dates and times were treated as floating-point, leading to much conversion and adjustinging. Eg. 12:30 was 12.30, so when adding 40 minutes getting 12.70, and then adjusting that to 13.10, No input validation was done. My colleague tried cleaning that up, but then got complaints from the users. They had discovered the "features" and were now using eg:
        January -6th
    meaning december 24th the previous year.

    My colleague had to remove the input validation again and keep the features.

  11. BMW MINI CD player as burglar alarm trigger by mccalli · · Score: 5, Interesting

    This was a fun one. I had one of the first MINI Coopers, and ordered it with the CD player ('Wave' option? Seem to remember that name). I forget exactly when I took possession of the car, but I think it was around September or October. Something like that.

    Anyway, at roughly 2:00am every morning the car alarm would go off, much to the 'delight' of myself, my neighbours and everyone in the vicinity. I'd go out, stop the alarm and then try to sleep. After which it would go off again, every hour or so.As if we weren't losing enough sleep with our then new-born daughter.

    The cause was eventually traced, and it's one of the more obscure bugs I've ever come across. Turns out that the car had a low-power rather than completely off mode, and the CD player retained a tiny amount of power going through it. When it was cold, say at 2:00am on an autumn morning for example, the CD player would detect that condensation was forming and would wake up the car's electrics to create some warmth to clear the condensation. This is deliberate, and quite clever I think.

    However, the problem came in that it did this too often and started causing a big drop in battery reserves. The security system interpreted this as an attempt to start the car by hotwiring it, and so the alarm would be set off. I'd come out to switch it off, then go back to bed on the cold autumn night at which point condensation would form again, the CD player would switch itself on again, the security system would sound the alarm again and a bleary-eyed version of me would stagger out to turn the alarm off again. At which point condensation would start to form again and...

    Bah.

    Cheers,
    Ian