[swift-evolution] [Proposal] autocreate parameter for optional values

[Saagar Jha]

If the compiler can figure out the type of the expression, you can use [:] in place of [NSObject: AnyObject], as below:

let config = URLSessionConfiguration.default
var headers = config.httpAdditionalHeaders ?? [:]
headers["Some-Additional-Info"] = "1992-08-01"

Saagar Jha



> On Jul 28, 2016, at 19:08, Kwanghoon Choi via swift-evolution <swift-evolution at swift.org> wrote:
> 
> Dear swifters. 
> 
> I have an proposal for autocreation of optional variables
> 
> This idea came from below situation
> 
> I have to addtional header to NSURLSessionConfiguration like this
> 
> let config = NSURLSessionConfiguration.defaultSessionConfiguration()
> config.HTTPAdditionalHeaders?["Some-Additional-Info"] = "1992-08-01"
> 
> here is the problem
> 
> how to be sure not nil for HTTPAdditionalHeaders in defaultSessionConfiguration
> 
> may be nil or not nil, I read api reference of HTTPAdditionalHeaders but, did't see  for value state of creation.
> 
> yeah, I know. it's optional. so may be I should thought it must be nil. but really must be? I think it's not very clear logic.
> 
> anyway, HTTPAdditionalHeaders was nil. so i have to solve, and solve like this.
> 
> let config = NSURLSessionConfiguration.defaultSessionConfiguration()
> var headers = config.HTTPAdditionalHeaders ?? [NSObject: AnyObject]()
> headers["Some-Additional-Info"] = "1992-08-01"
> 
> May be another way to solve this.
> 
> so I suggest autocreate parameter or something like that
> 
> NSURLSessionConfiguration have this variable
> public var HTTPAdditionalHeaders: [NSObject : AnyObject]?
> 
> change above things to like below
> public autocreate var HTTPAdditionalHeaders: [NSObject : AnyObject]? {
> 
> create { return [NSObject: AnyObject]() }
> 
> }
> 
> 
> 
> let headers = config.HTTPAdditionalHeaders must be return nil
> 
> but 
> 
> config.HTTPAdditionalHeaders["SomeThinkConvenient"] = "YEAH~"
> 
> this is automatically create Dictionary and set key and value
> 
> 
> 
> What about this idea, Dears?
> 
> 
> 
> Thank you for reading.
> 
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