Nithin Bekal

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Tabs vs. Spaces for Indentation

08 Jun 2011

A few days ago I was arguing with a friend about the right way to indent code. Being a spaces-for-indentation fanatic myself, I complained about the hard tabs he was using in one of his Github repos and he in turn expressed shock that I actually waste time on this space-for-indentation thing.

If you are an indentation fanatic, you would probably, like me, classify programmers into 4 categories:

  1. People indenting with spaces
  2. People indenting with tabs ‘\t’
  3. People who mix spaces and tabs
  4. People who don’t indent

Did I hear you mutter “That 4th type are NOT programmers”? Of course they aren’t. In fact, in my book they are right up there alongside Sauron’s minions, Lord Voldemort’s Death-Eaters, and Darth Vader and the Sith as the most evil creatures that ever walked on the earth.

Unfortunately for those of us that try to hold on to our sanity, there are hiring managers out there who hire these people and let them pollute others’ beautifully written code. As long as they are allowed to write code, we might as well accept the fact that they exist in the programming world.

Which brings me to the type 3 folks. Their mixture of tabs and spaces makes it a nightmare to read code, but at least you can convert the tabs in most editors and get something close to readable code. At least they try to indent, and that’s a lot better than code that’s fully left aligned. Anyway, if you’re one of the people doing this… stop it. Just stop. Please.

That finally leaves the two sets of programmers that indent exclusively using either spaces or tabs. Personally I prefer spaces, but that’s probably because I write Ruby code often and using two spaces for indentation is the common convention in the Ruby community.

Why use tabs?

Tabs for indentation has one clear advantage over spaces. You can customize how much indentation should appear. For instance, if your teammate likes 8 column indentation (what kind of people do you work with?) and you prefer 4 columns, well, you don’t have to do anything. Once you’ve set your editor to display 4 column tabs, you don’t have to worry about how many columns your teammates see. As long as you both consistently use hard tabs, you’ll both be fine.

Why use spaces?

Most Ruby and Python programmers would swear by spaces-for-indentation. People in both these communities almost unanimously agree with indenting with spaces and it’s especially important in Python because of its use of whitespace for delimiting blocks.

The best thing about this is that it makes the code look consistent everywhere. Since everybody in these communities uses the same indentation rules, it’s not much of a problem, but no such consensus in many other languages.

Conventions

While looking around for conventions in major open source projects on indentation, I came across the Linux coding style document:

Tabs are 8 characters, and thus indentations are also 8 characters. There are heretic movements that try to make indentations 4 (or even 2!) characters deep, and that is akin to trying to define the value of PI to be 3. Rationale: The whole idea behind indentation is to clearly define where a block of control starts and ends. Especially when you’ve been looking at your screen for 20 straight hours, you’ll find it a lot easier to see how the indentation works if you have large indentations.

I find this strange. Draconian almost. Eight character indentation seems so

  1. And yet one of the most important open source projects in the world imposes these rules, and some of the best programmers in the world follow them. In such cases, using tabs for indentation makes sense, because then heretics like me can set the tab width to 4 (or even 2! - what madness!) and happily read the code.

(To the author of the document quoted above: If you’ve been looking at your screen for 20 hours straight, that means you ought to be taking a break, rather than increasing indent levels on your program.) ;-)

Anyway, what’s most important about indentation is that you -and your team - do it consistently and follow the same guidelines. Here’s what Jeff Atwood of Coding Horror has to say of tabs v/s spaces in Death to the Space Infidels:

Choose tabs, choose spaces, choose whatever layout conventions make sense to you and your team. It doesn’t actually matter which coding styles you pick. What does matter is that you, and everyone else on your team, sticks with those conventions and uses them consistently.

Which he cheekily followed up with:

That said, only a moron would use tabs to format their code.

I certainly won’t disagree with that. The second part, especially.

Hi, I’m Nithin Bekal. I work at Shopify in Ottawa, Canada. Previously, co-founder of CrowdStudio.in and WowMakers. Ruby is my preferred programming language, and the topic of most of my articles here, but I'm also a big fan of Elixir. Tweet to me at @nithinbekal.