Cracking The Credit Card Code | MintLife Blog | Personal Finance News & Advice

This is probably the best presentation I have seen explaining how check digit routines work. We use these at work for non-credit card numbers, and usually you have to suffer through them once. If you are smart and you write proper object oriented code, you'll be able to reuse your check digit for say, Generic Airlines Frequent Flyer, as many times as you want since once they adopt the scheme odds are they'll stick for it for years.

When this turns challenging is when the spec documents are sloppy. I implemented one of these check digits for a customer in the hospitality industry, and their example case for the check digit routine had a tiny little redundancy error. The result? My check digit routine was WRONG, but it WORKED with the example account numbers. Fun times ...

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On sleep deprivation and Incan Monkey Gods

From: Dilbert comic strip for 08/03/1992 from the official Dilbert comic strips archive. I was trying to show this strip to a coworker who is dangerously toying with the harsh mistress that is Insomnia. What shocked me is how quickly I was able to look up the strip, which was published when he was just 11 years old, and two weeks before my just-out-of-college ass shipped out to US Army Basic Training.

Add custom speed settings to your ifit map workout

Ifit.com allows you to build a workout walk/race/bike route simply by clicking on a Google Maps interface. You can then use a compatible ifit-enabled workout machine to recreate the route automatically. The problem is that the user interface still isn't final, so there are features in place that aren't exactly obvious. For example, if you create a workout your machine starts at 1 MPH, because that's the default. But how to set it to start at say, 3 MPH? Easy, just switch from map view to graph view: That button switches from the Google Maps interface to a chart that allows you to visualize and control effort: You can't change the elevation, this is fixed due to the geography that you selected. But you can drag the yellow (speed line) to change the speed of your device. What if you want to have segments at different speeds? Easy, just click and drag and it will break the line, and you can drag each segment of the line independently: ...

Software Entropy and the Strangler Fig: Surviving a 20-Year-Old Codebase

Right now, I find myself fighting a three-front war. Front one is keeping a 20-year-old behemoth of a B2B application alive. We are talking about decades of legacy ASP.NET and VB.NET where two decades of tweaks, patches, and "temporary fixes" have become permanent, load-bearing pillars of the architecture. Every time I touch it, it feels like playing Operation with oven mitts on—spending 90% of my week untangling logic just so a simple bug fix doesn’t cause a ripple effect that crashes a critical service. Front two is modernizing the architecture. I am actively trying to implement a rudimentary Strangler Fig pattern—slowly carving out legacy functionality and pushing it into a clean, testable shared library project so we can actually run proper unit tests and stop the bleeding. Front three is modernizing the team. While keeping the lights on and quietly rebuilding the engine, I am also pushing a retraining effort to get my peers up to current framework versions and embracing ...

The Insomniac Coder

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