[swift-evolution] Proposal: Add function SequenceType.find()

[David Waite]

A version specifically for dealing with downcasts seems very special purpose to this particular use case, especially when you can just use flatMap.

-DW

> On Feb 18, 2016, at 2:01 PM, Thorsten Seitz via swift-evolution <swift-evolution at swift.org> wrote:
> 
> 
> Am 18.02.2016 um 20:36 schrieb Trent Nadeau via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>>:
> 
>> I would prefer a label on the first parameter, since you're not finding the NSButton type but instead elements having the type of NSButton.
>> 
>> subviews.find(havingType: NSButton.self, matching: { $0.state == NSOnState })
> 
> To comply with the guidelines I would expect a phrase like
> 
> subviews.findElement(havingType: NSButton.self, matching: { $0.state == NSOnState })
> subviews.find(instanceOf: NSButton.self, matching: { $0.state == NSOnState })
> 
> -Thorsten
> 
>> 
>> On Thu, Feb 18, 2016 at 4:37 AM, Marco Masser via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> 
>>> On 2016-02-18, at 00:46, Kevin Ballard via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>> 
>>> Alternatively you can write
>>> 
>>>     subviews.lazy.flatMap({ $0 as? NSButton }).find({ $0.state == NSOnState })
>> 
>> Just to reiterate my point: I very much prefer the version without any casts. I just think this is much clearer and doesn’t put the burden of thinking about accidental memory and speed overhead (when forgetting the “lazy”) on the caller every time:
>> 
>> subviews.find(NSButton.self, matching: { $0.state == NSOnState })
>> 
>> Also, there’s the goal of Swift being easy to learn. Which line do you think is easier to explain to newcomers?
>> 
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>> 
>> 
>> 
>> --
>> Trent Nadeau
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