Jay Paroline

There is an effort underway at GS to modify our framework to make writing code easier than ever before (for the second time). It’s a great idea in theory and the results of what I have seen so far certainly make doing certain things more convenient, which is great when you’re writing code.

But I can’t help but feel that we are perhaps barking up the wrong tree a bit.

Peter Hallam points out that programmers spend most of their time reading code, not writing it. So rather than focusing on making code easier to write, we should be sure that we are making it easy to read, understand and modify. Peter surmises that a 10% reduction in the time it takes to understand code is equivalent to a 100% reduction in the time that it takes to write code. That’s very significant.

One of the mantras I have heard a bit too much is “always favor composition over inheritance.” As Phil Haack points out, composition is great sometimes, but it’s not a perfect design either (because there isn’t one). Personally, I think it’s best to keep composition and inheritance in mind and always prefer whichever one going to lead to easy-to-understand code. Many times I find that to be inheritance. Sometimes the solution is even minor code duplication, such as having each page requiring authentication to do an explicit auth check rather than having the framework infer whether or not an auth check is required based on the name or, and I shudder at the thought, comments in the code.

(and how you handle what has been returned)

Things have been busy at Grooveshark, as usual. These past couple of days I have been hunting a bug both cthulu-like in its scary-strangeness and ninja-like in its stealthy manner. I went through all my code related to this particular project several times with a fine-toothed comb and didn’t catch it until today.

Turns out it wasn’t so strange after all. The fault was definitely mine, but PHP’s quirks certainly didn’t help matters any.
I was using array_search in a straightforward manner, not to find the particular position of an item but to find whether or not the item was in the array at all. The one thing about array_search, especially in the context of PHP’s loose typing, is that if it finds nothing it returns false. Of course, php happily treats false as zero, so how do you check to see if array_search is saying that it wasn’t found, or is saying that it’s the first element in the array? You have to check using strict equivalency, which I remembered, so I wrote my code like this:


$found = array_search('something', $arr);
if ($found === false) {
//handle what you do when it's not in there
}


then, a little while ago, specs changed and there was another case that had to be handled the exact same way as when ‘something’ wasn’t in $arr. So I did this:


$found = array_search('something', $arr);
$found = $found || (SOME_OTHER_CASE);
if ($found === false) {
//handle what you do when it's not in there
}


So in other words, when I went back and looked at that code later, I didn’t notice the triple equals instead of the double, so without much thought I assumed that $found was already a boolean, when it was really only a sometimes-boolean. In a strictly typed language this mistake would, of course, not have been possible. More practically, if array_search returned something other than practically-zero, I would have been able to explicitly handle that special case and store the result of that explicit handling as a boolean. If you read the documentation you will see that array_search actually returned NULL before version 4.2.0. I have to wonder why they decided to change it.

The reason this bug was so hard to find was because it was only a bug when the item being searched was the first item in the array, which it turns out is not that often. By the time I found that bug, there were hundreds of newer lines of code to check first.

Now that the bug is solved and now that I am far into this very technical post I think it’s safe to leak a tiny bit of information about what you, dear user, can expect to see in Grooveshark Lite in the near future: autoplay. We have decided that we want to be your personal DJ. Our tack on this feature aims to get around the chicken and egg problem: how do you build recommendations without user feedback, and how do you get user feedback if you don’t have recommendations to make them want to use the system? I’m not going to answer that question directly, but we hope that you will find the autoplay sessions to be enjoyable, and as you provide feedback to the system, we’ll take that data and make it even better.