8: Pointers! Computers Use Them Too.

If there’s one thing that scares people more than void, it’s got to be pointers. And rightfully so if they’re misused or you get somebody trying to explain them who’s already uncomfortable with them. This episode is going to rip the bandage off quick so we can move past this topic and soon you’ll wonder what all the fuss was about. I mean, really, we point to things all the time. Computers are just copying what we’ve been doing since childhood. You’ll learn how simple index cards with a location of an item can be thought of as pointers and the benefits of adding this extra level of indirection. Because with pointers, you can now organize your items one way yet find the items with a different system. If you get the chance, check out the Fundamental Theorem Of Software Engineering. It’s not really a theorem but it states that: We can solve any problem by introducing an extra level of indirection. In the podcast, I show you how to solve the problem of rearranging items on shelves while still being able to find the items. A system of pointers adds the extra layer of indirection needed. Listen to the full episode or read the full transcript below. Transcript Have you ever setup a forwarding address? People who don’t yet know your new address can continue to find you through your old address. This is a pointer because your old address now points to your new address. This is also a temporary pointer because eventually it will go away. The post office only gives you about 6 months. It has to go away because while it points to your new address, it also exists as the current address for whoever is now living at your old address. Because of this dual purpose, it’s not really a good example of pointers in programming. I mentioned it to get the explanation going and because it’s an obvious analogy that has some flaws. So what’s a pointer then in computer programming? Or what would be a better example of a pointer? Let’s go back to the rows and shelves of the last episode and imagine that you have a small part called a super widget. The super widget fits in a square box about 5 inches per side. Let’s also say that this part is rarely needed so you keep it somewhere at the back. You sometimes get phone calls asking if you have this part or that part and you think to yourself, “There’s got to be a better way to find out if we have a part than by walking to the row and shelf and looking.” Even organizing the parts so you can find them doesn’t help eliminate the long walk to check the availability of super widgets. But it’s the best you can do, right? At least you know exactly where to find each part. Then one day, you receive a new shipment of 3 super widgets and discover that the manufacturer decided to put them in bigger boxes. You need more shelf space because everything is already packed as tight as possible. You can’t just put the super widgets on a nearby empty shelf because that would mess up your careful system to be able to find them later. You’re in for a long week because you’re going to need to shift all the other parts in the same row over by just an inch to make room. And to make matters worse, you just went through a similar chore 2 weeks ago. Come to think about it, this has been an ongoing problem. You look at that empty shelf again and wonder. What if you could just put parts anywhere? Just find a spot that fits and use it. You’d still need some way to organize the parts so you could find them but does the organization really need to be based on the actual location of the parts? You have an idea and go get a bunch of small index cards and make a note on one of them that the super widgets are on row 27, shelf 4. Then you start recording the other parts each on a separate index card. You record each part’s location and as an afterthought, since you’re at it anyway, you record how many you have. It takes a while to record all the parts. But now, you can organize