blog.eridi.us

Philosophy for coding tricks

Mon, 30 Jan 2012 17:10:00 -0800

A lot of what we do in programming is defining a subset of the language that we’re comfortable working with. This is especially notable with C++, but is seen elsewhere. In our subset of the language we adopt a lot of little tricks and rules that reduce the mental burden of writing code. This way we can write code quickly without having to think about every single line. If your mental rule of thumb is good enough, then you can trust it to do the right thing. However if you come up with rules that contain edge cases that the code they’re replacing doesn’t have, then you’re doing yourself a disservice. For example, for object initialization if your mental rule is “nobody ever returns another object from [super init] besides self”, you might come up with the following boilerplate:

if ([super init] == nil) return nil;

You may think this is fine because if you’re subclassing something that can return a different object, obviously you’d actually write the “correct” code, right? The thing is, you’re just setting yourself up to fail. The mental trick you’ve employed means that you aren’t thinking about it when you’re writing it, and you’re highly likely to forget about the edge case until you hit the bug in the wild.

For this reason, mental tricks that you employ need to be constructed to be safe and always handle the edge cases, even if the edge cases don’t exist 99% of the time you employ the code. For example, the clasically recommended way to write an initializer in obj-c looks like

if ((self = [super init])) {
    // write code here
}
return self;

By always following this pattern, even if you know [super init] will always return self, you’ll be safe in the rare occasion that it actually doesn’t.

Another example of a mental trick I like to employ is the strict usage of ivars in -init/-dealloc. In most cases, calling a property setter in -dealloc isn’t going to cause a problem, but in rare cases it will introduce bugs in your application, either due to overridden setters or KVO. By restricting myself to ivars only in -init/-dealloc I’m protected against the edge cases no matter what class I’m currently working in. It frees me from the need to think about every property setter to make sure it’s safe to call in these environments. It also encourages cleaner code. If a property setter has a side-effect that I need to occur in -dealloc, then I can move that to a separate function that’s explicitly documented as being safe to call in -dealloc, and then I can call that inside of -dealloc instead of calling the property setter. This makes the side-effect immediately obvious in -dealloc and saves me from introducing bugs later if I modify the side-effecting function (since, as I said before, I’ve clearly documented that this gets called from -dealloc).

TinEye Safari Extensions

Sun, 13 Jun 2010 04:46:04 -0700

TinEye Safari Extensions:

TinEye is a cool reverse image search engine. It lets you take an image and search for it on the web, even finding uncropped, expanded, or unwatermarked versions of the image. Sadly, while TinEye…

CleanGoogle Safari extension

Thu, 10 Jun 2010 05:31:08 -0700

CleanGoogle Safari extension:

If you’re like anybody else that I know, you were rather shocked and appalled to see Google follow the likes of Bing and add background images to their home page. If you’re also like anybody else…

1Password extension loading in Snow Leopard

Wed, 02 Sep 2009 15:13:49 -0700

1Password extension loading in Snow Leopard:

One of the big changes in Snow Leopard is the move to 64-bit applications system-wide. This includes Safari. Unfortunately, this change breaks all of the Safari plugins out there, including mine….

Zynga is Hiring

Mon, 18 May 2009 14:48:38 -0700

Zynga is Hiring:

If you’ve been following me, you’re aware that I’ve been working at Zynga for the past two weeks. Well, they’re still hiring more people (and not just iPhone developers). You can see the available…

ExecTweets on the App Store

Mon, 18 May 2009 14:48:38 -0700

ExecTweets on the App Store:

My last iPhone contract app, ExecTweets for iPhone, is now on the App Store. This is the project that drove the creation of FeedParser (an open source Obj-C RSS parser). Anyway, it’s free, and…

Major FontLabel update

Mon, 18 May 2009 14:48:38 -0700

Major FontLabel update:

Last week I pushed out a major rewrite of FontLabel. This new version includes a category modeled after UIStringDrawing that enables you to draw text in custom fonts in your own drawRect:…

MyLifeIsAverage - Life Is Normal Today

Tue, 12 May 2009 22:27:23 -0700

MyLifeIsAverage - Life Is Normal Today

Starting a new job

Tue, 28 Apr 2009 18:01:57 -0700

Starting a new job:

This coming monday, I am going to stop being an iPhone contractor and start being a full-time employee of Zynga. While there, I will be working on developing iPhone games.

DNS-SD Browser is on the AppStore

Fri, 10 Apr 2009 18:15:40 -0700

DNS-SD Browser is on the AppStore:

DNS-SD Browser has finally been released on the iTunes AppStore.

DNS-SD Browser is the iPhone version of my popular desktop Bonjour Browser software. It enables you to view all of the Bonjour…

DNS-SD Browser

Fri, 10 Apr 2009 16:57:00 -0700

DNS-SD Browser:

DNS-SD Browser has finally been released in the iTunes AppStore. This is the iPhone version of my popular desktop Bonjour Browser application.

The latest screenshot of the upcoming Diablo 3

Sat, 31 Jan 2009 11:53:04 -0800

The latest screenshot of the upcoming Diablo 3

iPhone Protip: Fake navbar buttons

Thu, 22 Jan 2009 05:46:06 -0800

If you need to have a third button in your navigation bar, you’ve probably discovered already that you can’t add a UIBarButtonItem as you only have 2 slots for those, on the left and the right. There’s the titleView property, but you need to provide your own view and UIButton doesn’t have a style for bar buttons.

However, there is a reasonably easy solution. UISegmentedControl has a bar style that looks exactly like one of the buttons. The only problem is it doesn’t behave like a button. However, you can make a simple subclass that overrides the -touchesBegan:withEvent: and friends methods in order to make it behave like one after all. Now you can stick that in titleView and it looks just fine.

If you want it to be right-aligned on the bar, there’s another simple trick. Just create a UIView, set its frame to the bounds of the navbar, set your button as a subview right-aligned in the view and set the autoresizeMask to keep it there. UINavigationBar will resize the titleView to fill all the remaining space, which will mean your button is now right-aligned right next to the rightBarButtonItem.

iPhone Protip: nib top-level objects

Tue, 20 Jan 2009 01:00:00 -0800

When UIViewController loads a nib file, it does not retain all top-level objects in the nib (unlike MainWindow.nib where all top-level objects are retained). If you use top-level objects besides your view, you must make sure you implement the IBOutlets as retained properties.

Star Wars: Retold (By Someone Who Hasn’t Seen It) [VIDEO]

Thu, 15 Jan 2009 11:58:00 -0800

Star Wars: Retold (By Someone Who Hasn’t Seen It) [VIDEO]

Prince of Persia (PS3)

Sun, 04 Jan 2009 22:17:00 -0800

Prince of Persia (PS3):

The latest Prince of Persia game is a fresh start for the Prince of Persia series, focusing more on acrobatics and puzzles than on combat. I’ve only just started playing today, but so far I can say I love the visual style, the voice acting is great, and the writing is good. If you liked Sands of Time, I definitely recommend this. And there’s a version for the Xbox 360 or PC as well if you don’t have a PS3.

Just picked up Tumblrette and turned off auto-posting of my Twitter stream. Hopefully I’ll now...

Sun, 28 Dec 2008 14:40:05 -0800

Just picked up Tumblrette and turned off auto-posting of my Twitter stream. Hopefully I’ll now actually post things.

Sitting in Sanders Theatre waiting for the Christmas Revels to start. And it looks like Yo Yo Ma is...

Sat, 27 Dec 2008 15:03:27 -0800

Sitting in Sanders Theatre waiting for the Christmas Revels to start. And it looks like Yo Yo Ma is in the audience!

Installing World of Warcraft on my laptop so I can get my present from Grandfather Winter later

Thu, 25 Dec 2008 09:01:07 -0800

Installing World of Warcraft on my laptop so I can get my present from Grandfather Winter later

Merry Christmas!

Thu, 25 Dec 2008 09:01:06 -0800

Merry Christmas!