coding conventions

    Tab Convert

    That’s convert, with the stress on the first syllable. The noun, in other words. As in, “I am a tab convert.” A convert, that is, to using tabs for indentation of source code, instead of spaces.

    A Background of Spaces

    From the earliest time that I learned about the tabs vs spaces debate, I’ve been a spaces guy. This is at least partly because of the influence of my then-colleague Benjamin Geer. He has gone on to other, no doubt better, things, but he was probably the best programmer I’ve ever worked with. He introduced me to the idea that you should always use four spaces for indentation. The reason being that if you use tabs, people can have their editor’s tab size set to all sorts of different values, and it leads to source files not looking as you expect them to.

    Whereas spaces are spaces: you can’t go wrong with a space (or four).

    I’ve changed, though. I have become a convert, in my job, and maybe philosophically, to tabs.

    Stack Overflow Survey

    About a year ago there was a survey of developers on Stack Overflow. Among many questions, they asked about whether people used spaces or tabs. The detail that got most attention was that developers who use spaces were paid more on average than those who use tabs. I strongly suspect that correlation is not causation in this case, but it seemed noteworthy at the time.

    More interesting to me was the fact that more people used tabs, at 42.9% against 37.8%. I was surprised: I thought spaces had won years ago. Though I often wondered (sometimes publicly, and I’m surprised to see that was only last year) why the default setting for Eclipse was tabs.

    Maybe that default, and others like it, is part of the reason for the statistics. Most people don’t change defaults. On the other hand, surely developers are the kind of people who are most likely to change defaults?

    Anyway, after the survey came out there were various posts about it, notably John Gruber, who said he was “a devout user of tabs”. OK, he’s not a developer these days, but there were others who are who said similar things. The one that struck me was one that I can’t locate now that said “tabs are semantic.” In other words, pressing the tab key means “indent here.” Four spaces means… four spaces? Could be an indentation, could be something else.

    Everything Changes Imperially

    So I was primed for the idea of switching to tabs, even though I still used spaces in my own projects. And then I started my new job at Imperial College. When I first started looking at the code, I quickly realised that it was indented with tabs throughout. I checked with my co-worker who is the main contributor. He didn’t mind, but they had always used tabs.

    Obviously I didn’t want to introduce a mixture. That’s what really messes up the display of code in different editors. You have to be consistent within a project. So if I were to change the project to spaces I would have to change every file. That was an unnecessary step; and per the above, I was primed to use tabs. They’re semantic, after all.

    I switched my IDE to indent using tabs, with the tab-stop value set to 4. And so we proceed, tabbing away merrily.

    So far I prefer it this way.