Before I really got into development, I went through the entire archive of Joel on Software reading every single article. I like to think that it set me up with good foundational knowledge for professional software development, but that’s pretty hard to prove.
Recently I re-read the article Things You Should Never Do, Part I. With a lot more development experience under my belt, the article spoke to me much more strongly this time around.
I currently work on a large and highly-customised Magento installation. Our team likes to joke about Magento and how we have to battle with it to achieve business goals. These criticisms are often justified, sometimes in Magento core code and frequently with third-party modules.
When reading the Joel on Software article, though, I reassessed my opinion of Magento to some extent. I still think it’s a beast to work with, but you’ve got to admit that it is battle-hardened and in all of its complexity does manage to do its job correctly a lot of the time in very varied situations.
This part of the article felt most relevant to Magento’s situation:
“Back to that two page function. Yes, I know, it’s just a simple function to display a window, but it has grown little hairs and stuff on it and nobody knows why. Well, I’ll tell you why: those are bug fixes. One of them fixes that bug that Nancy had when she tried to install the thing on a computer that didn’t have Internet Explorer. Another one fixes that bug that occurs in low memory conditions. Another one fixes that bug that occurred when the file is on a floppy disk and the user yanks out the disk in the middle. That LoadLibrary call is ugly but it makes the code work on old versions of Windows 95.”
When working with Magento, you come across so much code that the above quote applies to. A lot of it is genuinely bad without a good justification, but now I’ve come to appreciate that ugly code is sometimes like that for a reason. From that I almost have a new-found respect for Magento (but not quite – I would never choose to use it); all that ugliness is powering a large sector of ecommerce across the web in a wide variety of environments and situations, and generally doing quite a consistent job of it (I still can’t bring myself to use the phrase ‘good job’ here).
A large part of the frustration of working with Magento is the high level of abstraction it starts at before slowly extending its way down to actually doing some work. This leads to two issues for developers: difficulty in isolating where the real work is done and safely making atomic changes; and the impact of that on the community and ecosystem that surrounds Magento.
I have mixed feelings about heavy abstraction in software design. When designing a system, it’s tempting to abstract heavily to allow flexibility in dealing with any possible change that might arise in future. Supposedly it’s possible to identify anything that might change and thus abstract around it in the design. What can often result from this approach, though, is a design that is so abstracted and flexible that it fails to clearly and concisely describe the problem domain. Instead, everything is described vaguely and even essential behaviour can become implicit and subtle rather than explicit and obvious.
Magento is an example of this. Simply understanding the current approach and behaviour is not trivial, which leads to bugs that may span tens of thousands of lines of code. That result is inevitable for Magento due to its goal of being totally flexible to every possible ecommerce situation that any business using it may encounter. With that design goal, everything must be as abstract as possible as nothing has any degree of safety from future change.
This then leads to a community surrounding Magento that takes wildly different approaches to a huge array of problems that the platform may need to solve for its users. Users and third-party vendors are encouraged to wade into this Jenga- like tower of abstraction, modifying, removing and inserting bricks at every level.
When the bugs emerge (and emerge they do), you find yourself stepping through what can arguably be called OOP spaghetti trying to determine at what level of the tower this particular problem is hiding. The way Magento leaps around between different levels of abstraction, with customised and third-party code mingled at various points, feels unpleasantly like working with
GOTO. This is compounded by PHP’s weak type system and relaxed approach to side-effects, which can make it difficult to reason about the intention and effects of the functions you’re looking at.
When encountering this situation, I keep wondering what the system would look like if it had instead been made with a focus on YAGNI. As I said above, YAGNI is the opposite of Magento’s approach, so Magento could never have been made that way. What I wonder about is how it would work out for an organisation that might have used Magento to instead build a minimalist, close-to-the-probem-domain system that only adds abstraction when it is clearly necessary to elegantly approach an existing situation. I’m not an expert on this, but my feeling is that that’s when the design patterns and abstraction should come in to produce an effective and manageable system, rather than trying to pre-empt any and every potential for change which is imagined before it ever occurs.
Here’s a nice quote from an interview with Pete Goodliffe that relates to this:
“If you don’t write enough code, it doesn’t do what it’s supposed to do, but just avoiding all those points of needless generality. Don’t make abstracts interfaces, don’t make deep hierarchies that don’t need to be extended, if you don’t need to extend them.”
My take on this turned into a bit of rant, which wasn’t my original intention when writing this article, but this does lead to a nice conclusion. That kind of ugly code is often ugly for a reason: both due to accumulated fixes for a variety of problems, but also because of a need to deal with excessively complex possibilities in one scope, which in turn can be a product of highly abstracted, flexible designs. It’s certainly a mixed bag.
I’d like to recommend a book I’ve been reading recently that I’ve found very relevant to these issues: Working Effectively with Legacy Code, by Michael Feathers. Not only does this book provide a useful set of approaches and tactics for dealing with this kind of situation (focusing largely on how to get legacy code under test in order to safely refactor it), it also presents a good attitude, which is to take on these types of systems as an interesting technical challenge rather than a horrible chore.
Finally, one more quote from the Fog Creek blog post:
“One thing I know about well crafted software that basically has the necessary complexity but none of the unnecessary complexity is when I look at it, it looks obvious. That is the key hallmark of some excellent code. You look at it and you just think, “You’ve been working on that for a while” and I look at it and I go, “That’s clearly right.” And you know it wasn’t simple to write. When you look at it the solution’s simple, the shape is simple. All I can say is, that’s what we should strive for.”