How to make successive method calls with less repetitive code in Swift?

Question

Here's an example from HockeyApp that generates the following code:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool { BITHockeyManager.sharedHockeyManager().configureWithIdentifier(API_KEY) BITHockeyManager.sharedHockeyManager().disableCrashManager = true BITHockeyManager.sharedHockeyManager().startManager() BITHockeyManager.sharedHockeyManager().authenticator.authenticateInstallation() return true }

Notice the repetition of BITHockeyManager.sharedHockeyManager() in each call. I'm looking for a syntax that does something like (pseudo code):

with BITHockeyManager.sharedHockeyManager() do { .configureWithIdentifier(API_KEY) .disableCrashManager = true .startManager() .authenticator.authenticateInstallation() }

Is there a way to do this in Swift?

Edit: After writing this question I noticed that Alamofire is using "chainable methods" , which actually is originally what I was looking for. This allows a neat syntax, as follows (code from http://nshipster.com/alamofire/):

Alamofire.request(.GET, "http://httpbin.org/get") .response { (request, response, data, error) in println(request) println(response) println(error) }

To use the corresponding syntax with HockeyApp would require modifying the BITHockeyManager class.

Martin R · Accepted Answer · 2015-01-05 13:17:34Z

6

I don't think that something like

with BITHockeyManager.sharedHockeyManager() do { .configureWithIdentifier(API_KEY) .disableCrashManager = true // ... }

is possible in Swift, but what you could do is to define a generic function

func with<T>(item : T, closure : T -> Void) { closure(item) }

which simply calls the closure with the given item as the argument, and then take advantage of the "trailing closure syntax" and "shorthand argument name" $0:

with( BITHockeyManager.sharedHockeyManager() ) { $0.configureWithIdentifier(API_KEY) $0.disableCrashManager = true // ... }

edited Jan 5, 2015 at 13:17

answered Jan 5, 2015 at 13:12

Martin R

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6 Comments

zisoft Over a year ago

Good solution but I think this does not make the code more readable and maintainable... :-)

Martin R Over a year ago

Well, it is just a suggestion and meant as a reply to "Is there a syntax to get rid of defining the manager?", which was originally in the question and later removed.

Markus Rautopuro Over a year ago

It's a good solution, and also answers the modified question.

Markus Rautopuro Over a year ago

... which makes me wonder if you can do the same with a prefix operator.

zisoft Over a year ago

@MartinR: Yes, fully agreed. It is just my opinion that I would not choose that way due to the bad readabilty of the code. The solution itself is very good!

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Markus Rautopuro · Accepted Answer · 2015-01-07 09:41:26Z

You can always use the following approach, which is a little bit shorter, but still requires repetition of the variable manager:

let manager = BITHockeyManager.sharedHockeyManager() manager.configureWithIdentifier(API_KEY) manager.disableCrashManager = true manager.startManager() manager.authenticator.authenticateInstallation()

I guess this is the best you can get. I'd do it the same way.

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