Swift Style Guide by GitHub | Hacker News Reader

Swift Style Guide by GitHub

github.com

88 pointshacker_user49 comments

What does Github write that uses Swift? I thought they didn't have an iOS app and I figured their desktop app was some node-webkit or electron based thing based on it being 27mb download.

This actually left me more curious than any of the rules in the style guide.

Swift is on track to be a general purpose language not only targeted towards iOS, OSX, tvOS, and Watch. There are already web servers written in Swift[1] so using Swift for backend work is increasingly more viable. They may have internal plans to implement some new products in Swift, but who knows.

[1] - https://github.com/izqui/Taylor

They may also have internal apps written using Swift which are not public. However it's also nice to have a public style guide.

My feeling is that they want a guide up now from the beginning before they proceed with creating Swift apps.

With Swift now open source and is an increasingly popular language to write brand new apps on Apple's platforms which consistent of iOS, OS X, watchOS, and tvOS.

The desktop app contains lots of Objective-C and Swift code. You can check it using `otool -o` on the binary to dump the __OBJC segment, or by opening it in Hopper.

Lost me at "Tabs, not spaces." :p

Tabs beat spaces in every single way;

- only press a single key instead of tapping 2 or 4 times.

- alter their width within your IDE to suit your preferences.

- they are "designed" to intent a piece of text with unlike spaces which are "designed" to break words.

But use whatever you like as long as it's consistent :)

Yeah, consistency trumps preference.

> But use whatever you like as long as it's consistent

I would add "as long it's consistent with the codebase and the practices of the project"

Mixing tabs and spaces in a project is very unpleasant and changing one for the other wreaks havoc in the blame functionality

    git blame -w …

We really shouldn't get into this, but I can't help myself.

- Every single text editor that's come after notepad.exe has had automatic tab/space conversion. Pressing tab inserts N spaces, pressing backspace un-indents N spaces, etc.

- In some languages, this is not a feature. 2-character tabs, using two tabs to indent for alignment:

    var myVar = 1,
        otherVar = 2,
        anotherVar = 3;

Opened later in an editor using 4-character tabs:

    var myVar = 1;
            otherVar = 2,
            anotherVar = 3;

- {}[]<> and more aren't used for anything close to their original literary intent.

Tabs should never be used for lining things up, for that very reason. In your example, you've stopped 'indenting' and started 'aligning'. And it's only 'working' because "var " % 2 == 0; other language keywords will screw that up.

Sounds to me like you're saying there's no objectively correct answer that works for all languages and situations, which I agree with.

There... is, actually. If you don't actually attempt to align the variable names, then what you're doing is "indenting items in a list", essentially.

In general, you should avoid aligning unless the readability gains are significant. Aligning things means that you end up re-aligning when you add or remove longer items. This increases maintenance and pollutes diffs (which also means code reviews and git logs).

My editor aligns things for me - no effort at all.

You are creating effort for the people who review your code. On their behalf, please stop, it's tedious.

I prefer tabs BUT ... don't you have to throw out any line-length requirements if you use them?

Nah just hard wrap at the line length.

Imagine everyone setting their preferred tab width and hard wrapping.

That'll be fun for looking at VCS diffs...

Well said. I see tabs as an accessibility feature.

https://leclan.ch/tabs

But like you said, consistency matters a lot more.

"- only press a single key instead of tapping 2 or 4 times."

I use spaces and I still only hit a single key.

Tabs beat spaces in every single way;

Spaces look the same in whatever application you might be using to view a source file, be it any number of random command line tools, or fully fledged IDEs.

Assuming monospaced font.

So setup your tab to insert four spaces, like every editor on the planet.

> only press a single key instead of tapping 2 or 4 times.

Consider changing your editor.

Ah, tabs are bad, because if you let people choose their own tab widths then it becomes impossible to align anything anymore. It makes it impossible to align anything which is != a tab width.

Tabs aren't "designed" for indenting text: they're a hangover from typewriters, where they were literally metal tabs used for creating tables. Tabs don't carry semantics - that's the job of the language's syntax. Tabs as a concept should be confined to history IMHO, especially their implementation in modern word processors, where they just give you ad-hoc semantic-less tables.

The tab key on the otherhand is great for indenting - in most sensible editors it will insert a configurable number of spaces. Perfect.

There is an easy solution to the alignment problem: don't align stuff.

I haven't used column alignment in at least 20 years. I don't miss it at all, and I'll never go back to aligning things.

Column alignment causes far too many problems. Once you give it up, any advantage of spaces over tabs disappears. Code written without alignment reads the same whatever you use for indentation, and it is even perfectly readable in a proportional font!

I've written a few comments on HN about the problems with column alignment and the advantages of an alignment-free style. Here are a couple of previous discussions with specific examples:

https://news.ycombinator.com/item?id=10206860

https://news.ycombinator.com/item?id=9469713

This is so very wrong....

> tabs are bad, because if you let people choose their own tab widths then it becomes impossible to align anything anymore.

In what world is that true. If you indent your code with tabs, and I indent your code with tabs and I show my tabs as 4 chars wide and you show yours and 8 EVERYTHING IS STILL ALIGNED. It's just greater or lesser levels of indentation. You only have problems when you MIX tabs and spaces. Be consistent in your use and you won't have problems.

> It makes it impossible to align anything which is != a tab width.

Yes. So? Don't mix tabs and spaces.

> Tabs aren't "designed" for indenting text: they're a hangover from typewriters, where they were literally metal tabs used for creating tables.

What is a table? It's a tool FOR ALIGNING MULTIPLE COLUMNS OF TEXT... so yes, they ARE designed for indenting text.

For a more fully thought out argument on why it's a dick move to use spaces as pretend tabs: http://weblog.masukomi.org/2010/07/26/why-you-should-never-i...

I agree, particularly with Elastic Tabstops

http://nickgravgaard.com/elastic-tabstops/

Oh god, not that one again. I have no idea which one I'm using and quite frankly, I don't want to know either.

Out of curiosity does anyone know the default for Xcode? Looking at my settings it has indent using 4 spaces and I don't remember ever setting it.

Also, the examples on the page all seem to use 4 spaces instead of a tab.

It is correct. Only fools presenting flawed arguments opine for spaces rather than tabs for indentation.

That's right, indentation, NOT alignment. Spaces are for alignment, tabs for indentation. Not tabs for indentation and alignment, not spaces for indentation and alignment, but rather tabs for indentation and spaces for alignment.

The thing that strikes me is how much shorter a Swift style guide is, compared to an Objective C one. E.g. https://github.com/raywenderlich/objective-c-style-guide

This fact tells a lot about the langage. The language is pretty strict as to what it allows to write and reduces the need of a style guide to specifying best practices.

I'm not so sure about "Make liberal use of vertical whitespace to divide code into logical chunks." — it's my tendency to add a lot of vertical whitespace as I write code, but the more I go back and remove it, the more I'm convinced that it wasn't really helpful and that whatever little help it did provide was far outweighed by how much less context could be seen on the screen at one time.

I think of it kind of like prose: we organize related sentences into paragraphs and then have little or no extra vertical whitespace between paragraphs. If you ever find yourself thinking you need some extra level of hierarchy division within a paragraph, you're likely really just needing a new paragraph.

Exactly right. The smallest unit of logical division in code is the function. It's not meaningless whitespace. Some programmers seem to like whitespace, but it's a purely aesthetic preference. No more or less.

> Fewer debates about aesthetics

Are you kidding? You just added one. De gustibus non est disputandum.

Dictatorial decree is a valid solution to some debates, especially the neverending ones. I actually think it's one of Golang's best features, having a built-in "go fmt" tool that automatically applies an opinionated style guide, which makes it so every single Go repo I find in the wild has code that's formatted in the manner to which I'm most accustomed.

Yes, Swift should do the same thing. Format on save. So much time is wasted on style guides.

If only Apple cared enough in XCode to provide one.

Yup. Amazing in Go. At first I was all (Python-esque) spaces, not tabs! Not only have I come over to the tabs side, but...

IT NO LONGER MATERS!

`gofmt`being run on save changes the game, and ensures consistency without beating people about the head with it. I wish more language had this feature.

> Not even leading indentation on blank lines.

Ugh. I wonder how is this a real issue?

Non-indented blank lines ARE an issue though - they make code editing more cumbersome, requiring pressing the tab key far more often.

Also, tabs are for bros.

If your editor doesn't do smart tabbing, I'm sorry for you. Not to mention that random trailing whitespace is just annoying.

Part of the problem is that Xcode (you know, the editor pretty much everybody will be using to write Swift) leaves blank lines indented. So to leave a blank line that doesn't have indentation, you press Return, and you get an indented blank line; you then need to press Backspace some appropriate number of times to get the cursor back to column 0; then you press Return.

(In Xcode's defence, the cursor is, then, at least indented.)

If you don't use Xcode, you might not realise how crap Xcode is.

While this is the default behavior, you can, at least in Xcode 7.2, check "Automatically trim trailing whitespace" and "Including whitespace-only lines" under "Text Editing" in Xcode's preferences.

It might help you to use the OSX keyboard shortcut cmd + shift + [left, delete]. The left variant will move you to the beginning of a line, delete will clear all preceding characters and put the cursor on column 0.

I'm on Xvim so I'd prefer to have non-indented blank lines for navigation with { and }. But I wouldn't suggest this guideline for projects where multiple devs since Xcode defaults to indenting blank lines. IMO you want to set yourself up for success as far as consistency goes, and that means sticking to defaults where possible.

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