“How do you approach a new codebase?”

aerial photography of city with river
Unrelated image from to make this post look nicer in social media shares.

Why yes I do love mining the internets for blog post ideas :)

This particular question is about learning a new codebase at work, but I think there’s plenty of stuff here that would carryover to learning the codebase of an opensource project you want to contribute to.

When you want to learn a new codebase, the very first thing you need to do is get it to build on your machine. Deliberately breaking things is an extremely useful tool when you want to understand a codebase, if you can’t even build the app you have no chance of figuring out if you broke it or not.

At work there should be another dev around who can sit down with you and help you get everything set up so you can compile, if you’re working on an opensource project you’re going to have to rely on docs, maybe a community chat like slack, gitter, etc, and sheer stubbornness.

Next you need to be able to run it or at least run the tests (if there are tests). This can be a lot more work than just getting the app to compile. For example, the app I work on at my own job compiles really easily but it won’t run unless you have all the environment variables set up correctly and the database and cache and everything installed. You’re probably going to want that coworker’s help here too. If you’re lucky your company has docs you can read and if you’re very lucky they’re even up to date, but at most places I’ve worked the development environment setup process was never written down, only passed down orally.

Quick aside: I’ve said this before, but if your company doesn’t have any docs, write them! Seriously, you’ll make things so much easier for the next dev, who might even be you. If your computer dies on you and you need to get setup again in a hurry, you’re going to be really grateful if you can follow the docs instead of desperately trying to remember how to do that one tricky bit.

Depending on how your app works you may also need help creating an account for yourself so you can actually log in and use it. Once you can build, run, and log in (if you need to), you can really start digging into the code.

What makes the most sense to me is starting from the UI and working my way in from there. It also really helps me to have a goal, like a bug to fix or a small feature to add. I get lost if I just sort of wander around a codebase trying to figure out how everything fits together, having a goal helps me focus.

It’s also totally okay to ask another dev for a quick overview of the app, having a bit of context can make it a lot easier to figure out how everything fits together. Customer documentation can be really helpful here. Sure, it won’t tell you which controller handles the data for the user details page, but it will tell you how to get there and what you can do there.

Eventually you’ve got to get in there and start looking around, though. I poke around the UI until I find a screen that looks like it could be related to the thing I want to do, then I copy some text from that screen (ideally something that looks distinctive) and search for it in the code. Most of the time this is helpful but sometimes the text you thought was distinctive really isn’t, you may have to search for a few different things before you find something that gets you useful results.

If the app is a webapp it often helps to open up the network tab in your browser dev tools and look at the calls the frontend makes to the server. If you’re not sure exactly which endpoint is actually getting called this can clear things right up. Don’t be afraid to add more logging either, just try to remember to clean it up when you’re done :) I do that all the time when I’m trying to figure out exactly what my app is up to.  If you want to get fancy you may even be able to attach a debugger to your running application and step through the code one statement at a time. I have this irrational dislike of doing that (I find stepping through the code tedious and would rather just throw in another System.out.println), but if it works for you, great!

Once you find the right server calls it should be fairly simple to trace your way back through the code all the way to the database (or other data store) if you need to. I mostly work in Eclipse, so I’m working from the assumption I have good IDE support and can easily navigate the project once I decide where to start. If you aren’t using an IDE that makes it really easy to find the definition of a class or method, you’re just going to have to do a lot of searching.

IDEs can only do so much for you, though. When I’m trying to figure out a complicated part of the code I’ll sort of draw myself a map so I don’t get lost. That is, I’ll write down, either on paper or in a text file, exactly what calls the method I’m looking at, and what calls those methods, and what calls those methods until I’m clear on how everything fits together and where exactly that one bad parameter came from.

Like I said earlier, breaking stuff on purpose can be a great way to verify that you understand how the pieces fit together. Once you think you know where the problem is / where you should add your new feature, try commenting out the body of a method and seeing if things break the way you expect. If they do, great! If they don’t, hey at least you found out sooner rather than later that you were wrong about how it works. Another good way to break things is to give them bad data. I do that when I want to know if my request is even making it to the part of the code I’m interested in – if it doesn’t break the way I expected then I know I’m wrong about what the code is actually doing.

If one screen or endpoint or whatever just doesn’t make any sense to you, try another one! You may just need to see more of the app before things start coming together, or you may have just had the bad luck to stumble across an especially tricky part of the app. Keep trying, and ask for help if you need it, you’ll get it.

Speaking of asking for help: most developers hate doing it, but it really is okay to ask for help if you get stuck. Especially if you’re a junior, it takes practice to get good at finding your way around new codebases. Five minutes of explanation by someone who knows the code could save you hours of confusion and frustration. The faster you get up to speed on that new codebase, the more help you’ll be to your coworkers, so it’s actually in their best interests to interrupt them (after trying to figure it out on your own, of course) to ask for help.

One last tip: it takes months, literally multiple months, to really be productive at a new development job. If you feel stupid and useless, that’s a) not true, and b) totally normal. You would never tell a new hire that they’re an idiot for not instantly figuring out a new codebase, so try to be that nice to yourself, okay?

Code smell: temporary fields

Several puffins are clustered on a grassy hill or shore while two more puffins come in for a landing.
Unrelated image from to make this post look nicer in social media shares and also because puffins are cute.

Today’s code smell is temporary fields. Like with all code smells, sometimes these aren’t a problem at all. For example, it’s pretty normal to have a user object with a bunch of optional fields. Sometimes you have users who just start out with a username and a password and fill in their profiles later and sometimes you have fields for stuff like social media accounts that only some users will ever fill in, but sometimes fields that only sometimes have a value are a problem.

One of the ways people try to fix the problem of a long parameter list is to make some of those parameters into fields and then set them later if they need to. Unfortunately that’s not really any better because it just hides some of the confusion under the rug instead of actually getting rid of it. Instead of it at least being obvious you have too many parameters, now you have a bunch of fields that may or may not get used depending on what the object is up to and you have to go hunting to figure out what’s going on.

Since professional programmers read code much more often than we write it, it’s a huge waste of time to have to go on an exploratory mission every time you need to understand that code again. If you do end up needing to update that code, best of luck figuring out which fields are important and whether your refactor / bug fix / new feature broke anything.

I had a heck of a time finding a code example for this code smell but fortunately so did Mark Seemann, who was frustrated enough by that to write not just an example of the smell but of how to refactor it too.

If you find this smell in your code, what do you do about it?

Pulling out the temporary bits into their own object and just using that is a good option (if that works for your code, of course). Isolating the fiddly bit makes the rest of the object cleaner and makes it clearer what the fiddly bit is up to. You can also add a null object (a special object where you put whatever defaults you use when one of your temporary fields is null). That way your normal processing code can be clean and simple instead of littered with null checks. Sometimes that just makes things more complicated, so it’s a bit of a judgement call.

If you’re having trouble figuring out what an object even does because most of its fields are null most of the time, see if some refactoring helps. You can always put it back the way it was if it’s worse afterwards :)

Arrogance is definitely a blocker

an orange and white jet plane seen from below against a blue sky with fluffy white clouds
Unrelated image from to make this post look nicer in social media shares.

The latest The Workplace question to inspire me to write a whole post is How do you counter the argument that “Arrogance isn’t a blocker”? I don’t understand why a professional would ever say that arrogance isn’t a blocker, but I’ve sure got opinions on how to counter that argument!

First of all, software development is a team sport. Sure, side projects and prototypes can be built by individuals, but the vast, vast majority of business software is built by teams, which means that communication is everything.

Are you going to go out of your way to communicate with the arrogant jerk on your team? No you are not. Nobody does that. Even if you really need to you’re going to put it off as long as possible. Yes that’s not ideal, and you can make the argument that it’s illogical, but let’s be real, humans have emotions and we don’t like dealing with jerks. To have good communication on your team you have to make it as painless as possible.

Arrogance is also a literal blocker to ideas. Arrogant jerks make people scared to speak up about ideas they aren’t completely sure about because they don’t want to make themselves targets. The bigger the jerk the more scared people get until nobody speaks up at all. Jerks also make people scared to try things – if a jerk is looking for any excuse to shit on you of course you’re not going to try anything that could possibly fail. With a bad enough jerk, nobody on the team grows as a programmer because they never try anything they haven’t done before.

Jerks also make your team avoid code reviews, at least if the jerk is involved. Nobody wants to hear that everything they built is terrible and the jerk could do it 1000 times better even if there are a couple of valid needles in the haystack of outright meanness. You can be sure no one will volunteer to review the jerk’s code either, which means standards start slipping, bugs may get into prod – not because code reviews are specifically about finding bugs but because code reviews are great for catching “this is really complicated and I’m having trouble following it, can you pull it apart and simplify it?” and that prevents bugs – and if somebody needs to change the jerk’s code nobody will know where to start because nobody reviewed their code.

And a jerk’s code often really needs reviewing. In my (thankfully limited) experience, jerks who think they’re smarter than everyone else write overly complicated code that no one else can follow to prove how extraordinarily clever they are. This has been known to backfire when it turns out that not even the oh-so-clever jerk can follow that code. Even if anyone is willing to review a jerk’s code, it’s not likely to improve that code because jerks rarely take feedback well. If they did, they’d stop being jerks!

Yet another way jerks harm your product is by ramming their ideas though by making every disagreement or discussion a huge fight. Eventually the rest of the team will get tired of having that fight over and over and let the jerk have their way, if only so they can stop talking about it. Just like with avoiding communicating with a jerk, you can argue that it’s short-sighted to prioritize avoiding a fight right now over dealing with the long term fallout of bad decisions, but you’ll get farther by expecting people to act like people than you will by expecting them to act like emotionless robots.

Finally, why should any non-jerk on your team bother to do their best when you let a jerk get away with writing bad code, refusing to listen to anyone else’s ideas, and making everyone around them feel terrible? If you won’t avoid hiring a jerk for any other reason, do it because all of your devs who can get a better job will do that just so they don’t have to spend all day at work with a jerk. Life is too short to work with jerks!

It doesn’t work unless it all works together

a dish of small red berries surrounded by more of the same berries
Unrelated image from to make this post look nicer in social media shares.

Or, let’s talk about context some more!

So last week I talked about how you can’t know if code is good or bad without knowing the context, what you’re actually trying to accomplish with that code, what was most important when it was written (priorities change, that doesn’t mean that the way the code was written at the time wasn’t perfectly reasonable for the context it was written in).

But there’s more to context than that! You also can’t know whether your code is any good in isolation. In other words, unit tests are not enough and can never tell you whether your code actually works. No seriously, they can’t. That’s because your code doesn’t work unless the whole app works, and the only way you can tell whether the whole app works is with end-to-end testing.

It’s great if all the pieces work according to your unit tests, I’m not knocking those, but they can’t tell you the whole story. Only integration tests can do that.

If you haven’t run into integration issues yet, just wait, it’ll happen :) Maybe your controller doesn’t validate user input quite the same way as the service that handles business logic does. Maybe one layer tolerates nulls and another one flips out and throws NPEs. Maybe the front-end and the back-end disagree just slightly on the format of the JSON that gets passed back and forth. Maybe one layer doesn’t return the exact error codes another layer/object/service was expecting.

Hell, maybe everything is great except for some missing assets on the frontend. That’s not covered by an integration test but it’s not really unit test territory either. Some stuff just has to be looked at by a human. Yes, it’s possible to automate frontend testing but if your UI changes very often at all then it may not be worth the trouble of reworking your tests every time it changes. Plus computers are kind of terrible at stuff like “this text doesn’t line up nicely with this text box,” so you’re going to need a human to look at your UI anyway.

It would be great if unit tests were all you need, and if you have really comprehensive unit tests you will catch most of your problems, but in the real world things break not just within components but between them. An application isn’t just a collection of models, views, and controllers (assuming you went with a MVC architecture), it’s also the interactions between those components. If you aren’t testing those interactions, you just aren’t testing enough.

Of course, even integration tests have their limits. I once broke production by changing a part of the system that I thought was unrelated to the part that broke. It was not :( (also cache invalidation is the worst). Integration tests are great for things you know are related, but sometimes you just need a human to click around in the app and notice that when you change setting A, feature B that seems unrelated doesn’t see the update.

If you possibly can, learn from my mistakes: it doesn’t work unless it all works together.


a railway bridge supported by brick arches surrounded by lush green jungle
Unrelated image from to make this post look nicer in social media shares.

So I was browsing questions late one night, as you do, and came across an interesting one: How to explain business priorities to a programmer.

That one didn’t go at all the way I thought from the title. It turns out the business priorities actually did make sense (the business had this wild idea that queries, even especially complicated ones, should take less than 4 hours to run) and the programmer was being unreasonably rigid in following “best practices”.

But weirdly, one of the answers said that both parties were wrong – that the programmer shouldn’t have been so attached to having nice looking code and the manager shouldn’t have insisted on using an anti-pattern. What? The anti-pattern (using raw SQL instead of the ORM) improved performance by multiple orders of magnitude! If performance matters at all, you cannot possibly tell me that massively improving performance was the wrong thing to do.

Okay, there is some nuance there :) If your ORM performs that badly it’s likely not configured right for your situation, so it might be better in the long term to fix your config than to keep writing custom SQL for every query that’s the least bit complicated. On the other hand, if you don’t have an expert handy who can tune your ORM config, it might be easier to ditch it, at least for the more complicated queries, and just write some SQL. Or hey, how about a compromise? Use a stored procedure, that’s what they’re for! If it’s a query you run a lot, it might even make sense to make a view for it.

No matter what you end up doing, it’s still not wrong to use a supposed “anti-pattern” if you have a good reason to do it. It’s the context that makes something a bad idea, even the best idea can turn bad if you use it the wrong way. The only way to know whether your “anti-pattern” is actually a bad idea for your particular situation is…. to look at your particular situation! You can’t just say something is an anti-pattern without knowing what the person using that anti-pattern is trying to accomplish.

Let’s look at another datebasey example. It’s generally considered a bad idea to denormalize your database, every database design course will tell you so. Normalizing your database ensures all of your data is always right by isolating everything that can change independently. Since you don’t usually bother to keep data at all if you don’t care if it’s all accurate, you almost always want your data nicely normalized.

But sometimes correctness isn’t the absolute most important thing. Let’s take browser or mobile games, for instance. If your game takes too long to load, your players will just go do something else and they might not ever come back. It’s much more important to be fast than it is to be perfect if you want to make money on a game like that. And if something does go wrong and a player gets mad because their data didn’t get saved correctly, you can just give them game currency until they’re happy again.

In a situation where performance is more important than correctness, normalization is the anti-pattern. Like I said, it’s all about context!

To be clear, there are some things that are just a terrible idea no matter what you’re doing. I don’t care how clever you think you are, your variable names need to make sense. And no matter how well it performs, if your system is so confusing than no one can make updates, then it’s a bad system. But for the most part whether or not something is an anti-pattern is about what you’re trying to accomplish more than it’s about the “anti-pattern” itself.

Everybody likes code that makes sense to them, and everybody likes to feel like they’re doing things the right way, but rigidly following “best practices” just isn’t good enough. If it doesn’t help you achieve your greater goals for your application (ie not just gold-plating your code, but providing value to your users or customers), it’s just not a good idea no matter how many experts call it a best practice.

And yes, that means you can’t know if your code is good or bad without knowing exactly what you’re trying to do. Welcome to professional programming!

Be a better programmer while still having a life: part 12

a waxing moon a little over half full against a deep blue sky
Unrelated image from to make this post look nicer in social media shares.

Keep it simple!

It sounds obvious, but I have wasted so much time debugging problems that turned out to be something ridiculously simple like my browser cache being outdated, having forgotten to deploy my code, having made my updates in my local database instead of the staging database, etc, etc. Better developers are more productive, and you know what instantly makes a person more productive? Wasting less time!

Double checking extremely simple obvious things can save you massive amounts of time. Like I said earlier, a little self-doubt is good for you. If you can’t ever doubt yourself at all, you’re going to waste a lot of time on silly mistakes you could have just double-checked.

This can be really really hard to remember as a dev, so don’t feel bad if you mess it up sometimes. My best guess is that’s a side effect of working with complicated problems all the time, so we assume the problem has to be more complicated than just having deployed the wrong code like a dope.

Another great way to keep things simple is to build the simplest possible solution for your problem. This is such a common problem that we have an acronym for it already: YAGNI (you ain’t gonna need it). Before you write more code ask yourself “Do I actually need this?” Protip: if you actually need the thing it will be obvious. If you don’t actually need it, don’t build it. Yes, things should be somewhat flexible, but there’s a limit.

Names are a great clue to whether you’ve built something so flexible that all it’s really doing is adding complexity. If you can’t guess what your object/function/module is for by looking at its name, it’s probably too vague. Using Java reflection is also a bad sign :P

Another way to check whether you’re building something too flexible is to try to explain it to someone else. If they can’t follow what on earth you’re doing, it’s definitely too vague. Even if they can follow your explanation, another person who isn’t attached to the terribly clever idea you came up with may be a lot more willing to say “No, we don’t actually need this, this, or this. That part is really cool, though.”

You can also try asking yourself if there’s anything you could possibly take out of your design. If you were doing the thing manually (just imagine your database lookups are done in a filing cabinet or giant binder instead), what would be different? Would there be fewer steps? Fewer people/processes/forms/approvals involved? This can be a tough one for programmers because for many of us, super complicated “solutions” make us feel smart and we love to feel smart.

I’m not going to pretend I’m any sort of UI expert, but this definitely applies to UI too. Do you really need a setting for everything? No! Make a decision already, if you’re going to leave everything up to the user, what are you even for? At least provide a sensible default setting and hide the fiddly stuff no one cares about under an “advanced” tab or something.

You know who failed at keeping it simple? Yep, it’s Google bro. Hey, if he didn’t want to be used as a terrible example over and over he should have been a better engineer. Given the choice between ignoring all of the existing science about gender differences in humans and making up a ridiculous and complicated fairy tale about how even though sexism obviously exists that couldn’t possibly be the reason there are fewer women than men in tech (let’s just ignore the fact that programming started out as a job for women while the men physically built the computers), no it must be some bizarre feature of our silly ladybrains, and the simple and obvious explanation that sexism exists, dude went with the most complicated possible explanation.

The more complicated your idea, solution, or design is, the more chances it has to fail. That’s still true even if your argument wasn’t built on sand in the first place. Simplicity, on the other hand, tends to work a lot better. The fewer moving parts you have, the fewer things you have to worry about holding in your head while you build it. As a bit of an aside, if you’re ever wondered why even extremely expensive software produced by armies of highly paid contractors is so often terrible and buggy, it’s because there are too many moving parts for our poor fleshy brains to keep track of.

Simplicity is incredible timesaver, for both you and your team. Simplicity in your code reduces the number of bugs you create, and avoiding creating bugs is orders of magnitude faster than fixing them. It also makes it easier to fix your bugs when you do run into them. Simplicity in your design can be the difference between a project that actually goes into production and does something useful, and something that just never quite gets launched. Simplicity in your problem solving helps you catch silly mistakes that waste hours of your time, so keep it simple!

Be a better programmer while still having a life: part 11

an alarm clock with a weathered, rusty face sits on a rustic wooden table
Loosely related image from to make this post look nicer in social media shares.

Don’t be a time thief. More precisely, if a decision has been made let it stay made.

This tip won’t necessarily change your personal output a whole lot, although you will have more time for your own work if you don’t waste it rehashing old decisions, but it will be fantastic for your team’s productivity. Being a better programmer isn’t just about how much you personally get done, it’s also about how much your whole team gets done. If you make your team better then congrats, you’re a better developer!

You will have to deal with decisions you don’t like as a developer. I’m not saying that’s a good time, but that’s not just life as a developer, it’s life in general. You can either accept those decisions like a grownup, or you can waste everyone’s time by fighting the same battles over and over.

Now, if something has substantially changed, like a new tool has been released or there has been an announcement that an open source library is no longer being actively developed, then it may make sense to reopen a closed discussion. But if you just don’t like the decision, you’re wasting everyone’s time. Even if you are technically right it’s generally faster to rework your codebase to recover from a decision that didn’t pan out than to have the same meeting over and over. It’s not just about the single decision, it’s about how you use your time.

It’s also about morale. It’s incredibly frustrating when you have meeting after meeting and finally decide something, only to have someone drag it all back up again a few weeks later. What was the point of all the earlier meetings if a decision that’s been made doesn’t stay made? If you want people to stop bothering to share their opinions, that’s the way to do it. Like I said last time, you have to be open to the idea that you could be wrong. You need your team’s ideas to make the best decision you can, and you can’t possibly get anyone’s real ideas when you convince them that it doesn’t matter what they say.

Arguing about things that are purely a matter of opinion is time-theft too. Curly brace on the same line as the method declaration vs the next line? tabs vs spaces? line width? No professionals bother to argue about that at work (the bar is a different story, however :) ), we pick a coding standard, set our IDEs to autoformat our code correctly and move on with our lives. Some arguments simply are not worth the time it takes to have them.

Speaking of arguments that have been had over and over and are a profound waste of everyone’s time, biology simply does not and never has explained the lack of women in computer science. We seem to drag this argument back up every few years in tech and every time it’s as foolish as it was last time. Google bro is simply the latest to waste thousands of hours of everyone’s time with ideas that have been debunked over and over. A grownup, not to mention a competent developer, would never have wasted everyone’s time with an argument that’s been hashed out dozens if not hundreds of times already. You simply can’t have someone like that on your team if you ever want to get anything done – even a competent developer, which Google bro certainly is not, couldn’t offset the collective productivity lost to rehashing well understood decisions over and over.

It’s perfectly normal to want to undo a decision you don’t like, just like it’s perfectly normal to want to stay in bed on a cold, wet morning and it’s perfectly normal to want to buy lunch and skip packing one. Wanting, however, is different from doing if you’re a grownup and you just can’t be a good developer without being a grownup. Even a lone hobbyist faces frustration and disappointment, you can either let those stop you in your tracks or you can set them down and make yourself useful.

Be a better programmer while still having a life: part 10

a metal framework tower holding up power lines is silhouetted against a dark sky that appears to be photoshopped because it is purple
Unrelated image from to make this post look nicer in social media shares.

A little bit of self-doubt is good for you! That might sound weird but hear me out. Doubting yourself just enough to accept the fact that you don’t know everything and will be wrong sometimes is incredibly useful in software development. So many projects have died when the thing that everyone assumed would be easy (or at least doable) turned out not to be. If you can accept that you could be wrong and do a little double checking, you can save yourself so much pain.

While we’re on the subject, if you ever hear the words “it’s done, we just need to integrate it” you should be very very afraid. Not only is the thing not done, but it’s not going to be done any time soon. I admit I’m generalizing from a small sample here, but I’ve never seen the assumption that integrating a new feature will be easy turn out to be accurate.

In general, if you’ve never used that API before, don’t assume it will be easy. Read the docs really thoroughly too – just because it sounds like that API does what you need doesn’t mean it actually does. I’ve been burned by that before and you probably will be too. Same thing for libraries you haven’t used before. Just because you think a library should work a certain way doesn’t mean it actually does. In case you weren’t already worried enough, don’t forget that sometimes the docs are outdated, missing, or just plain bad, too. There’s more than one reason building a very simple proof of concept first is such a good idea.

Like I said earlier, don’t assume you understand the problem either. Talk to people until you’re sure you understand why that feature should exist, not just what it should do. Talk to your team lead, talk to other departments, ideally talk to someone who is actually going to use the thing (I know this isn’t feasible for everyone but it’s really great if you can manage it). The assumption that you’re right about what people need kills projects too. You would think that would be an obvious thing to check, but judging by the horror stories in the news about massive government projects that turn out not to do what the front line staff actually need, it’s not obvious at all.

Seriously, I can’t stress enough how dangerous assumptions are to projects. That’s how projects end up months if not years late and massively over budget if they get delivered at all. Refusing to admit you could ever be wrong kills projects too. The real problem, underneath the assumption that integrating that API will be easy to integrate, is the assumption that you’re right and don’t need to check.

In addition to killing projects, failing to question your assumptions can also lead you to make a complete fool of yourself, a la google bro. If he had questioned any of his assumptions, if he could have faced the possibility he could ever be wrong about anything at any time ever, he would be a far better engineer. As it is he clearly can’t be trusted not to make wild assumptions that will doom his projects, and if you can’t trust someone to check their own assumptions you simply can’t trust them to work as a senior engineer. One simple definition of engineering levels is that junior developers need adult supervision, intermediate developers can work on their own, and senior developers are adult supervision. If you can’t bring yourself to accept that you could ever be wrong about anything, then you can’t competently supervise anyone.

Too much self doubt is obviously completely unproductive, and you can never know everything there is to know about your project before you build it, but a little self doubt is enormously useful and tremendously underrated. In tech we seem to place so much emphasis on always being perfectly sure of yourself but not only is that an unreasonable goal, it’s not even useful. What’s useful is understanding that the most brilliant writers still need editors, and the most brilliant programmers still need input from their teams. Nobody is right absolutely all of the time, the word for people who think they are is “delusional.”

Admit you could be wrong and you’ll end up with the right answer a lot more often.

Be a better programmer while still having a life: part 9

brown wooden wheel on an old cart with fallen leaves around it on the ground.
Vaguely related image from to make this post look nicer in social media shares.

Don’t reinvent the wheel! I’ve touched on this before, but it definitely merits its own post.

A huge part of becoming a better developer is understanding when you don’t need to write new code to solve a problem. The more code you write, the more code you have to maintain, the more chances you have to screw it up, and the more time it takes to write it. So before you write new code, see if there’s a library, a plugin, a product, a design pattern, or a best practice that solves your problem. At least see if anyone wrote an article or blog post about a similar problem and learn from what they did.

To be fair, sometimes what you need really isn’t well served by an existing trustworthy product or library and you do need to write your own custom code, but that needs to be an informed choice, not a reflex.

What I think makes a product trustworthy is active development and a large userbase. The main advantages of using a library instead of writing your own code is that you don’t have to update it and that most of the bugs have been worked out already because so many people use it. By all means use a small library that isn’t maintained if it’s convenient and not a core part of your project, but for the love of god don’t depend on a framework/database/core part of your project that isn’t actively maintained and/or doesn’t have any users. That will just end in tears.

You also don’t want to import a library for every little thing, the more libraries you import the more bloated your project becomes and the more chances you have to run into a bug in one of them (and let’s not forget the left-pad debacle), but for stuff that would take more than a few hours to write, see if somebody else already wrote it.

For example, writing your own regex to validate email addresses is almost certainly a waste of time. Are you really going to write a better validator than the Apache Commons EmailValidator? No, you’re not. And do you want to have to maintain it forever even if you do write a great validator? No, you don’t. So use the library and move on with your day.

Yes, writing code is way more fun than integrating a library, but when you’re at work your job is to get results. If writing your own code gets the best result, do that, but if integrating a library gets the best result, do that instead. Of course, to understand what gets the best results, be it a library, a whole product, an API, a design pattern or whatever else, that means you have to understand what’s out there.

As a bit of an aside, that’s why the Google bro is an incompetent engineer – his ridiculous screed shows he either didn’t read or didn’t understand any of the existing research about personality differences between men and women (spoiler: there aren’t any statistically significant ones). While junior engineers get a pass on not searching for or not understanding existing libraries, senior engineers do not. If you can’t Google (see what I did there :D) existing research or existing libraries, you simply are not operating at a senior engineer level.

Sometimes it is useful to reinvent the wheel – modern wheels with inner tubes and shock absorbers make riding in a modern car a lot more comfortable than riding in the first cars with their solid wheels (Google bro’s wheel, on the other hand, is square and the axel is off center, which is just embarrassing). If you can’t do better than existing wheels, just use what’s already out there and save yourself some time.

Ironically, admitting that you aren’t the greatest developer who ever lived makes you a better developer. Accepting that actively maintained, well-used libraries are often better than what you would write on your own not only saves you a lot of time, but also makes your final product better.

Code smell: long parameter list

a set of train tracks in an overgrown field curves off into the distance
Unrelated image from to make this post look nicer in social media shares.

Today’s code smell is long parameter lists. If you have lots and lots of parameters, something is likely going wrong.

Odds are good your method is just doing too much, which leads to confusing code that’s hard to understand and change. Another reason lots of parameters causes problems is that when you call that method, it’s very easy to accidentally get two parameters of the same type in the wrong order (not that that’s ever happened to me or anything).

How do you fix it?

Well, if you can break your method into separate methods that each do just one thing, do that. Not only does that solve the problem of a long, confusing, easy to mess up list of parameters, it also fixes the related problem of your method being confusing because it does too many things.

Another option if you can’t break up your method is to make a new object that holds all the parameters. Having named fields in the new object makes it a lot easier to keep track of which value goes where. If you already have an object that most or all of the parameters come from, it’s often simpler just to pass that along instead of pulling values out and passing those into the method you’re calling.

However, the more objects your caller and callee have in common, the more closely coupled they are. If your classes aren’t already closely coupled you’re probably fine to add another object they both use, but if they already have a lot in common then you should think about whether you really need that object. Of course, if your classes are extremely closely related they should maybe just be one class, but that’s a separate code smell.

And if breaking the big method into smaller ones means that the smaller ones absolutely always have to be called together, it’s probably better to leave it as one big method with lots of parameters. If you have to just remember what order to call the smaller methods in you’re asking for trouble, you will definitely mess that up sooner or later. A huge part of being a good programmer is accepting that it’s very very easy to mess it up and trying to avoid the most obvious pitfalls.

Like the other code smells, long parameter lists aren’t an absolute certainty you need to change your code, but I personally think they’re an especially strong sign that your design could be better. It’s just so easy to accidentally switch parameters, and even if you manage to keep them all straight it’s still a serious hassle to call a method with a huge list of parameters.

You know your codebase better than I do, though. Do what makes sense for your particular situation and don’t worry too much about my personal pet peeves :)