Tabs vs. Spaces

A friend asked on G+ recently about tabs vs. spaces. A lot of people agreed with what I said so I thought I’d turn it into a proper post.

There’s a good summary here: http://www.jwz.org/doc/tabs-vs-spaces.html. This is also a link Jeff Atwood has in his post on the subject.

So why are spaces preferred except tabs? Tabs have the nice feature of being both more compact, and the display of the code in an IDE can be customized (I prefer shorter indents, some prefer larger). Spaces are more verbose in a lot of ways. But I’m not going to go over pros and cons with using them because, frankly, they’re not the reason.

Spaces are preferable to tabs because, like the Zen of Python says, explicit is better than implicit. Explicit in the sense that it is more compatible in more places.

PEP8 tells us to limit lines to 79 columns, because our code may be running on fixed-width terminal windows, and python is a scripting language, so people would be looking at the actual code on those terminal windows. As opposed to compiled code, where you’re generally not going to look at or edit the code on those terminal windows.

Speaking of terminals. There are a lot of times we’re editing code in unfamiliar places. That’s not just something like a terminal window. It is an unfamiliar text editor. It is an editor embedded into some program. It is a diff tool. It is any number of places we may need to write or debug code outside of our primary editor/IDE. Who knows what happens when you hit ‘tab’? How are things configured? Why bother with the ambiguity?

Well nothing is stopping you from requiring tabs for your studio, and breaking python’s PEP rules, and educating and configuring everyone’s editors to use tabs. However, the first time you need to go in and edit some code you find on the internet or download through pip or easy_install, you’re going to screw up and create a syntax error. Not only that but nearly every IDE can be easily configured to use spaces instead of tabs for both indenting and dedenting. And where you’re not sure of the default, or don’t want to configure it, you can just use spaces and backspace.

So for python, there’s no reason to use tabs. Just don’t do it. You’re using a language that is dependent upon whitespace for code structure. You need to take it seriously and remember you and your code is part of the larger python community. It isn’t about preference, it is about compatibility.

If you aren’t using a whitespace-dependent language, feel free to establish a standard and enforce it. Just never do it with python.