Re: [swift-evolution] [Pitch] Detecting and working with Optionals from Any

[John McCall via swift-evolution]

> On Jun 22, 2016, at 9:12 AM, Charlie Monroe  wrote:
> 
> Please consider the following code:
> 
> let myString: String? = "Hello"
> let anyValue: Any = myString
> let obj: AnyObject? = anyValue as? AnyObject // nil, since it's 
> Optional, String being struct,
>// no implicit bridge to AnyObject. 
> (myString as AnyObject will
>// create _NSContiguousString).
> 
> if let optionalAny: AnyObject? = anyValue as? AnyObject? { // Error - can't 
> downcast from Any
> // ...
> }
> 
> if let optionalAny: AnyObject? = anyValue as? AnyObject { // nil
> // ...
> }
> 
> if let optionalAny: AnyObject? = asOpt(anyValue) { // Optional
> if let value = optionalAny { // value is _NSContiguousString
> value.dynamicType
> }
> }
> 
> This behavior is IMHO incosistent at best. Should this be considered correct 
> behavior or a compiler bug?

The inability to cast from Any to an optional is a bug.

John.

> 
>> On Jun 22, 2016, at 5:59 PM, L. Mihalkovic > > wrote:
>> 
>> 
>> 
>> On Jun 22, 2016, at 5:51 PM, John McCall > > wrote:
>> 
>>> 
 On Jun 22, 2016, at 12:15 AM, L. Mihalkovic via swift-evolution 
 > wrote:
 
 Func asOpt(v:Any) -> Optional {
   If let val = v as? T {
 Return val
   }
   Return nil
 }
 Regards
 LM
 (From mobile)
>>> 
>>> This is just:
>>>   return v as? T
>> 
>> Had more code where i took it from... I thk it is one of these simple thgs 
>> that u never forget but may not be immediate to thk abt. Maybe worth adding 
>> to doc comment for Optional<> (forgive if is there already)
>> 
>>> 
>>> John.
>>> 
 
 On Jun 22, 2016, at 7:11 AM, Charlie Monroe via swift-evolution 
 > wrote:
 
> Unfortunately, this is not as easy, because automatic bridging won't be 
> applied:
> 
> let myString: String? = "Hello"
> let anyValue: Any = myString
> 
> myString as? AnyObject // _NSContiguousString
> anyValue as? AnyObject // nil, since String is struct
> 
> let array: [String]? = ["Hello"]
> let anyArray: Any = array
> anyArray as? AnyObject // nil
> anyArray as? [AnyObject] // nil
> array as? AnyObject // ["Hello"]
> 
> And this goes for strings, arrays, dictionaries and possibly other types. 
> Which means that you need to handle manually all of the bridging to ObjC 
> types, which has really grown in Swift 3, taking into account all the 
> Foundation types that are now structs.
> 
> Should this then be considered compiler bug that bridging isn't taken 
> into account?
> 
> Nevertheless, I'd still find it useful exposing the isOptional() function 
> as well as the asOptional which would allow a cast from Any to 
> Optional which is not possible at all at this moment since any such 
> cast will pick up the Optional first:
> 
> let myString: String? = "Hello"
> let anyValue: Any = myString
> if let value = anyValue as? Any {
> value.dynamicType // This is still Optional, not naively just 
> the value of the optional
> }
> 
> 
> 
>> On Jun 21, 2016, at 8:18 PM, Joe Groff > > wrote:
>> 
>> 'as?' should already do this. If you have an Any that contains an 
>> Optional and cast 'any as? T', you'll get the value inside the 
>> Optional if there is one, or the cast will fail if the optional is nil 
>> or the type doesn't match.
>> 
>> -Joe
>> 
>>> On Jun 20, 2016, at 11:00 PM, Charlie Monroe via swift-evolution 
>>> > wrote:
>>> 
>>> I've recently written a CoreData editor on iOS which automatically 
>>> generates UI based on the model which is described using classes such 
>>> as PrimitiveProperty, etc. Since it automatically sets the value on the 
>>> entity, it needs to convert the value to AnyObject in order to pass it 
>>> to setValue(_:forKey:), so it needs to be able to detect whether the 
>>> value is Optional and in case it is, either transform the non-nil value 
>>> to AnyObject (String -> NSString, Array -> NSArray, ...). Which is 
>>> currently really hard to achieve: 
>>> 
>>> var obj: IndexPath? = IndexPath()
>>> let anyValue: Any = obj
>>> anyValue.dynamicType /// Optional.Type
>>> 
>>> /// Using only anyValue, determine if it's Optional and retrieve its 
>>> value if 
>>> /// non-nil as AnyObject.
>>> func isOptional(anyValue: Any) -> Bool {
>>>// Error: Cannot downcast from 'Any' (aka 'protocol<>') to a 

Re: [swift-evolution] [Pitch] Detecting and working with Optionals from Any

[L. Mihalkovic via swift-evolution]

> On Jun 22, 2016, at 5:51 PM, John McCall  wrote:
> 
> 
>> On Jun 22, 2016, at 12:15 AM, L. Mihalkovic via swift-evolution 
>>  wrote:
>> 
>> Func asOpt(v:Any) -> Optional {
>>   If let val = v as? T {
>> Return val
>>   }
>>   Return nil
>> }
>> Regards
>> LM
>> (From mobile)
> 
> This is just:
>   return v as? T

Had more code where i took it from... I thk it is one of these simple thgs that 
u never forget but may not be immediate to thk abt. Maybe worth adding to doc 
comment for Optional<> (forgive if is there already)

> 
> John.
> 
>> 
>>> On Jun 22, 2016, at 7:11 AM, Charlie Monroe via swift-evolution 
>>>  wrote:
>>> 
>>> Unfortunately, this is not as easy, because automatic bridging won't be 
>>> applied:
>>> 
>>> let myString: String? = "Hello"
>>> let anyValue: Any = myString
>>> 
>>> myString as? AnyObject // _NSContiguousString
>>> anyValue as? AnyObject // nil, since String is struct
>>> 
>>> let array: [String]? = ["Hello"]
>>> let anyArray: Any = array
>>> anyArray as? AnyObject // nil
>>> anyArray as? [AnyObject] // nil
>>> array as? AnyObject // ["Hello"]
>>> 
>>> And this goes for strings, arrays, dictionaries and possibly other types. 
>>> Which means that you need to handle manually all of the bridging to ObjC 
>>> types, which has really grown in Swift 3, taking into account all the 
>>> Foundation types that are now structs.
>>> 
>>> Should this then be considered compiler bug that bridging isn't taken into 
>>> account?
>>> 
>>> Nevertheless, I'd still find it useful exposing the isOptional() function 
>>> as well as the asOptional which would allow a cast from Any to 
>>> Optional which is not possible at all at this moment since any such 
>>> cast will pick up the Optional first:
>>> 
>>> let myString: String? = "Hello"
>>> let anyValue: Any = myString
>>> if let value = anyValue as? Any {
>>> value.dynamicType // This is still Optional, not naively just 
>>> the value of the optional
>>> }
>>> 
>>> 
>>> 
 On Jun 21, 2016, at 8:18 PM, Joe Groff  wrote:
 
 'as?' should already do this. If you have an Any that contains an 
 Optional and cast 'any as? T', you'll get the value inside the Optional 
 if there is one, or the cast will fail if the optional is nil or the type 
 doesn't match.
 
 -Joe
 
> On Jun 20, 2016, at 11:00 PM, Charlie Monroe via swift-evolution 
>  wrote:
> 
> I've recently written a CoreData editor on iOS which automatically 
> generates UI based on the model which is described using classes such as 
> PrimitiveProperty, etc. Since it automatically sets the value on the 
> entity, it needs to convert the value to AnyObject in order to pass it to 
> setValue(_:forKey:), so it needs to be able to detect whether the value 
> is Optional and in case it is, either transform the non-nil value to 
> AnyObject (String -> NSString, Array -> NSArray, ...). Which is currently 
> really hard to achieve: 
> 
> var obj: IndexPath? = IndexPath()
> let anyValue: Any = obj
> anyValue.dynamicType /// Optional.Type
> 
> /// Using only anyValue, determine if it's Optional and retrieve its 
> value if 
> /// non-nil as AnyObject.
> func isOptional(anyValue: Any) -> Bool {
>// Error: Cannot downcast from 'Any' (aka 'protocol<>') to a more 
>// optional type 'Optional<_>'
>return anyValue is Optional
>return anyValue as? Optional != nil
>...
> }
> 
> Unless there are major reasons why it's not exposed, I'd propose 
> introducing a new function isOptional(anyValue: Any) -> Bool, which would 
> simply call Builtin.isOptional just like _isOptional does in 
> Builtin.swift. (which pretty much is just taking the current _isOptional, 
> removing underscore and marking it public).
> 
> However, this still doesn't help with the issue of retrieving the value 
> of the Optional. You now know the value in `anyValue` is Optional, but 
> there is no good way to cast it to e.g. Optional. Here we're 
> getting into a vicious cycle that Any can be an Optional which is Any.
> 
> My second part of the proposal introduces another function:
> 
> func asOptional(anyValue: Any) -> Optional?
> 
> Which will:
> - return nil if !isOptional(anyValue)
> - return a non-nil value only if `anyValue` contains in fact an Optional 
> of type T.
> 
> Usage:
> 
> if let anyObjOptional: AnyObject? = asOptional(anyValue: anyValue) {
>if let anyObj = anyObjOptional {
>// anyObj is now the actual content of the optional.
>}
> }
> 
> As a sidenote, this is my current workaround:
> 
> private protocol _XUOptional {
>var objectValue: AnyObject? { get }
> }
> 
> extension Optional: 

Re: [swift-evolution] [Pitch] Detecting and working with Optionals from Any

[John McCall via swift-evolution]

> On Jun 22, 2016, at 12:15 AM, L. Mihalkovic via swift-evolution 
>  wrote:
> 
> Func asOpt(v:Any) -> Optional {
>   If let val = v as? T {
> Return val
>   }
>   Return nil
> }
> Regards
> LM
> (From mobile)

This is just:
  return v as? T

John.

> 
> On Jun 22, 2016, at 7:11 AM, Charlie Monroe via swift-evolution 
> > wrote:
> 
>> Unfortunately, this is not as easy, because automatic bridging won't be 
>> applied:
>> 
>> let myString: String? = "Hello"
>> let anyValue: Any = myString
>> 
>> myString as? AnyObject // _NSContiguousString
>> anyValue as? AnyObject // nil, since String is struct
>> 
>> let array: [String]? = ["Hello"]
>> let anyArray: Any = array
>> anyArray as? AnyObject // nil
>> anyArray as? [AnyObject] // nil
>> array as? AnyObject // ["Hello"]
>> 
>> And this goes for strings, arrays, dictionaries and possibly other types. 
>> Which means that you need to handle manually all of the bridging to ObjC 
>> types, which has really grown in Swift 3, taking into account all the 
>> Foundation types that are now structs.
>> 
>> Should this then be considered compiler bug that bridging isn't taken into 
>> account?
>> 
>> Nevertheless, I'd still find it useful exposing the isOptional() function as 
>> well as the asOptional which would allow a cast from Any to Optional 
>> which is not possible at all at this moment since any such cast will pick up 
>> the Optional first:
>> 
>> let myString: String? = "Hello"
>> let anyValue: Any = myString
>> if let value = anyValue as? Any {
>> value.dynamicType // This is still Optional, not naively just 
>> the value of the optional
>> }
>> 
>> 
>> 
>>> On Jun 21, 2016, at 8:18 PM, Joe Groff >> > wrote:
>>> 
>>> 'as?' should already do this. If you have an Any that contains an 
>>> Optional and cast 'any as? T', you'll get the value inside the Optional 
>>> if there is one, or the cast will fail if the optional is nil or the type 
>>> doesn't match.
>>> 
>>> -Joe
>>> 
 On Jun 20, 2016, at 11:00 PM, Charlie Monroe via swift-evolution 
 > wrote:
 
 I've recently written a CoreData editor on iOS which automatically 
 generates UI based on the model which is described using classes such as 
 PrimitiveProperty, etc. Since it automatically sets the value on the 
 entity, it needs to convert the value to AnyObject in order to pass it to 
 setValue(_:forKey:), so it needs to be able to detect whether the value is 
 Optional and in case it is, either transform the non-nil value to 
 AnyObject (String -> NSString, Array -> NSArray, ...). Which is currently 
 really hard to achieve: 
 
 var obj: IndexPath? = IndexPath()
 let anyValue: Any = obj
 anyValue.dynamicType /// Optional.Type
 
 /// Using only anyValue, determine if it's Optional and retrieve its value 
 if 
 /// non-nil as AnyObject.
 func isOptional(anyValue: Any) -> Bool {
// Error: Cannot downcast from 'Any' (aka 'protocol<>') to a more 
// optional type 'Optional<_>'
return anyValue is Optional
return anyValue as? Optional != nil
...
 }
 
 Unless there are major reasons why it's not exposed, I'd propose 
 introducing a new function isOptional(anyValue: Any) -> Bool, which would 
 simply call Builtin.isOptional just like _isOptional does in 
 Builtin.swift. (which pretty much is just taking the current _isOptional, 
 removing underscore and marking it public).
 
 However, this still doesn't help with the issue of retrieving the value of 
 the Optional. You now know the value in `anyValue` is Optional, but there 
 is no good way to cast it to e.g. Optional. Here we're getting 
 into a vicious cycle that Any can be an Optional which is Any.
 
 My second part of the proposal introduces another function:
 
 func asOptional(anyValue: Any) -> Optional?
 
 Which will:
 - return nil if !isOptional(anyValue)
 - return a non-nil value only if `anyValue` contains in fact an Optional 
 of type T.
 
 Usage:
 
 if let anyObjOptional: AnyObject? = asOptional(anyValue: anyValue) {
if let anyObj = anyObjOptional {
// anyObj is now the actual content of the optional.
}
 }
 
 As a sidenote, this is my current workaround:
 
 private protocol _XUOptional {
var objectValue: AnyObject? { get }
 }
 
 extension Optional: _XUOptional {
var objectValue: AnyObject? {
switch self {
case .None:
return nil
case .Some(_):
return self! as? AnyObject
}
}
 }
 
 if let optional = anyValue as? _XUOptional {
let object = optional.objectValue

Re: [swift-evolution] [Pitch] Detecting and working with Optionals from Any

[Charlie Monroe via swift-evolution]

Nice!

Would you consider this as something that should be part of the language? IMHO 
working this out takes much more time than it should and these two functions 
would definitely help out a lot.

> On Jun 22, 2016, at 9:15 AM, L. Mihalkovic  
> wrote:
> 
> Func asOpt(v:Any) -> Optional {
>   If let val = v as? T {
> Return val
>   }
>   Return nil
> }
> Regards
> LM
> (From mobile)
> 
> On Jun 22, 2016, at 7:11 AM, Charlie Monroe via swift-evolution 
> > wrote:
> 
>> Unfortunately, this is not as easy, because automatic bridging won't be 
>> applied:
>> 
>> let myString: String? = "Hello"
>> let anyValue: Any = myString
>> 
>> myString as? AnyObject // _NSContiguousString
>> anyValue as? AnyObject // nil, since String is struct
>> 
>> let array: [String]? = ["Hello"]
>> let anyArray: Any = array
>> anyArray as? AnyObject // nil
>> anyArray as? [AnyObject] // nil
>> array as? AnyObject // ["Hello"]
>> 
>> And this goes for strings, arrays, dictionaries and possibly other types. 
>> Which means that you need to handle manually all of the bridging to ObjC 
>> types, which has really grown in Swift 3, taking into account all the 
>> Foundation types that are now structs.
>> 
>> Should this then be considered compiler bug that bridging isn't taken into 
>> account?
>> 
>> Nevertheless, I'd still find it useful exposing the isOptional() function as 
>> well as the asOptional which would allow a cast from Any to Optional 
>> which is not possible at all at this moment since any such cast will pick up 
>> the Optional first:
>> 
>> let myString: String? = "Hello"
>> let anyValue: Any = myString
>> if let value = anyValue as? Any {
>> value.dynamicType // This is still Optional, not naively just 
>> the value of the optional
>> }
>> 
>> 
>> 
>>> On Jun 21, 2016, at 8:18 PM, Joe Groff >> > wrote:
>>> 
>>> 'as?' should already do this. If you have an Any that contains an 
>>> Optional and cast 'any as? T', you'll get the value inside the Optional 
>>> if there is one, or the cast will fail if the optional is nil or the type 
>>> doesn't match.
>>> 
>>> -Joe
>>> 
 On Jun 20, 2016, at 11:00 PM, Charlie Monroe via swift-evolution 
 > wrote:
 
 I've recently written a CoreData editor on iOS which automatically 
 generates UI based on the model which is described using classes such as 
 PrimitiveProperty, etc. Since it automatically sets the value on the 
 entity, it needs to convert the value to AnyObject in order to pass it to 
 setValue(_:forKey:), so it needs to be able to detect whether the value is 
 Optional and in case it is, either transform the non-nil value to 
 AnyObject (String -> NSString, Array -> NSArray, ...). Which is currently 
 really hard to achieve: 
 
 var obj: IndexPath? = IndexPath()
 let anyValue: Any = obj
 anyValue.dynamicType /// Optional.Type
 
 /// Using only anyValue, determine if it's Optional and retrieve its value 
 if 
 /// non-nil as AnyObject.
 func isOptional(anyValue: Any) -> Bool {
// Error: Cannot downcast from 'Any' (aka 'protocol<>') to a more 
// optional type 'Optional<_>'
return anyValue is Optional
return anyValue as? Optional != nil
...
 }
 
 Unless there are major reasons why it's not exposed, I'd propose 
 introducing a new function isOptional(anyValue: Any) -> Bool, which would 
 simply call Builtin.isOptional just like _isOptional does in 
 Builtin.swift. (which pretty much is just taking the current _isOptional, 
 removing underscore and marking it public).
 
 However, this still doesn't help with the issue of retrieving the value of 
 the Optional. You now know the value in `anyValue` is Optional, but there 
 is no good way to cast it to e.g. Optional. Here we're getting 
 into a vicious cycle that Any can be an Optional which is Any.
 
 My second part of the proposal introduces another function:
 
 func asOptional(anyValue: Any) -> Optional?
 
 Which will:
 - return nil if !isOptional(anyValue)
 - return a non-nil value only if `anyValue` contains in fact an Optional 
 of type T.
 
 Usage:
 
 if let anyObjOptional: AnyObject? = asOptional(anyValue: anyValue) {
if let anyObj = anyObjOptional {
// anyObj is now the actual content of the optional.
}
 }
 
 As a sidenote, this is my current workaround:
 
 private protocol _XUOptional {
var objectValue: AnyObject? { get }
 }
 
 extension Optional: _XUOptional {
var objectValue: AnyObject? {
switch self {
case .None:
return nil
case .Some(_):
return self! as? 

Re: [swift-evolution] [Pitch] Detecting and working with Optionals from Any

[L. Mihalkovic via swift-evolution]

Ext Optional {
 Func ifUnwraps(_ h: T->()){
  Switch self
Case .Some(let v):
  If let t=v as? T { h(t) } // invoke if T matches
Def:
  Brk
 }
Regards
LM
(From mobile)

> On Jun 22, 2016, at 9:15 AM, L. Mihalkovic  
> wrote:
> 
> Func asOpt(v:Any) -> Optional {
>   If let val = v as? T {
> Return val
>   }
>   Return nil
> }
> Regards
> LM
> (From mobile)
> 
>> On Jun 22, 2016, at 7:11 AM, Charlie Monroe via swift-evolution 
>>  wrote:
>> 
>> Unfortunately, this is not as easy, because automatic bridging won't be 
>> applied:
>> 
>> let myString: String? = "Hello"
>> let anyValue: Any = myString
>> 
>> myString as? AnyObject // _NSContiguousString
>> anyValue as? AnyObject // nil, since String is struct
>> 
>> let array: [String]? = ["Hello"]
>> let anyArray: Any = array
>> anyArray as? AnyObject // nil
>> anyArray as? [AnyObject] // nil
>> array as? AnyObject // ["Hello"]
>> 
>> And this goes for strings, arrays, dictionaries and possibly other types. 
>> Which means that you need to handle manually all of the bridging to ObjC 
>> types, which has really grown in Swift 3, taking into account all the 
>> Foundation types that are now structs.
>> 
>> Should this then be considered compiler bug that bridging isn't taken into 
>> account?
>> 
>> Nevertheless, I'd still find it useful exposing the isOptional() function as 
>> well as the asOptional which would allow a cast from Any to Optional 
>> which is not possible at all at this moment since any such cast will pick up 
>> the Optional first:
>> 
>> let myString: String? = "Hello"
>> let anyValue: Any = myString
>> if let value = anyValue as? Any {
>> value.dynamicType // This is still Optional, not naively just 
>> the value of the optional
>> }
>> 
>> 
>> 
>>> On Jun 21, 2016, at 8:18 PM, Joe Groff  wrote:
>>> 
>>> 'as?' should already do this. If you have an Any that contains an 
>>> Optional and cast 'any as? T', you'll get the value inside the Optional 
>>> if there is one, or the cast will fail if the optional is nil or the type 
>>> doesn't match.
>>> 
>>> -Joe
>>> 
 On Jun 20, 2016, at 11:00 PM, Charlie Monroe via swift-evolution 
  wrote:
 
 I've recently written a CoreData editor on iOS which automatically 
 generates UI based on the model which is described using classes such as 
 PrimitiveProperty, etc. Since it automatically sets the value on the 
 entity, it needs to convert the value to AnyObject in order to pass it to 
 setValue(_:forKey:), so it needs to be able to detect whether the value is 
 Optional and in case it is, either transform the non-nil value to 
 AnyObject (String -> NSString, Array -> NSArray, ...). Which is currently 
 really hard to achieve: 
 
 var obj: IndexPath? = IndexPath()
 let anyValue: Any = obj
 anyValue.dynamicType /// Optional.Type
 
 /// Using only anyValue, determine if it's Optional and retrieve its value 
 if 
 /// non-nil as AnyObject.
 func isOptional(anyValue: Any) -> Bool {
// Error: Cannot downcast from 'Any' (aka 'protocol<>') to a more 
// optional type 'Optional<_>'
return anyValue is Optional
return anyValue as? Optional != nil
...
 }
 
 Unless there are major reasons why it's not exposed, I'd propose 
 introducing a new function isOptional(anyValue: Any) -> Bool, which would 
 simply call Builtin.isOptional just like _isOptional does in 
 Builtin.swift. (which pretty much is just taking the current _isOptional, 
 removing underscore and marking it public).
 
 However, this still doesn't help with the issue of retrieving the value of 
 the Optional. You now know the value in `anyValue` is Optional, but there 
 is no good way to cast it to e.g. Optional. Here we're getting 
 into a vicious cycle that Any can be an Optional which is Any.
 
 My second part of the proposal introduces another function:
 
 func asOptional(anyValue: Any) -> Optional?
 
 Which will:
 - return nil if !isOptional(anyValue)
 - return a non-nil value only if `anyValue` contains in fact an Optional 
 of type T.
 
 Usage:
 
 if let anyObjOptional: AnyObject? = asOptional(anyValue: anyValue) {
if let anyObj = anyObjOptional {
// anyObj is now the actual content of the optional.
}
 }
 
 As a sidenote, this is my current workaround:
 
 private protocol _XUOptional {
var objectValue: AnyObject? { get }
 }
 
 extension Optional: _XUOptional {
var objectValue: AnyObject? {
switch self {
case .None:
return nil
case .Some(_):
return self! as? AnyObject
}
}
 }
 
 if let optional = anyValue as? _XUOptional {
let object 

Re: [swift-evolution] [Pitch] Detecting and working with Optionals from Any

[L. Mihalkovic via swift-evolution]

Func asOpt(v:Any) -> Optional {
  If let val = v as? T {
Return val
  }
  Return nil
}
Regards
LM
(From mobile)

> On Jun 22, 2016, at 7:11 AM, Charlie Monroe via swift-evolution 
>  wrote:
> 
> Unfortunately, this is not as easy, because automatic bridging won't be 
> applied:
> 
> let myString: String? = "Hello"
> let anyValue: Any = myString
> 
> myString as? AnyObject // _NSContiguousString
> anyValue as? AnyObject // nil, since String is struct
> 
> let array: [String]? = ["Hello"]
> let anyArray: Any = array
> anyArray as? AnyObject // nil
> anyArray as? [AnyObject] // nil
> array as? AnyObject // ["Hello"]
> 
> And this goes for strings, arrays, dictionaries and possibly other types. 
> Which means that you need to handle manually all of the bridging to ObjC 
> types, which has really grown in Swift 3, taking into account all the 
> Foundation types that are now structs.
> 
> Should this then be considered compiler bug that bridging isn't taken into 
> account?
> 
> Nevertheless, I'd still find it useful exposing the isOptional() function as 
> well as the asOptional which would allow a cast from Any to Optional 
> which is not possible at all at this moment since any such cast will pick up 
> the Optional first:
> 
> let myString: String? = "Hello"
> let anyValue: Any = myString
> if let value = anyValue as? Any {
> value.dynamicType // This is still Optional, not naively just the 
> value of the optional
> }
> 
> 
> 
>> On Jun 21, 2016, at 8:18 PM, Joe Groff  wrote:
>> 
>> 'as?' should already do this. If you have an Any that contains an 
>> Optional and cast 'any as? T', you'll get the value inside the Optional 
>> if there is one, or the cast will fail if the optional is nil or the type 
>> doesn't match.
>> 
>> -Joe
>> 
>>> On Jun 20, 2016, at 11:00 PM, Charlie Monroe via swift-evolution 
>>>  wrote:
>>> 
>>> I've recently written a CoreData editor on iOS which automatically 
>>> generates UI based on the model which is described using classes such as 
>>> PrimitiveProperty, etc. Since it automatically sets the value on the 
>>> entity, it needs to convert the value to AnyObject in order to pass it to 
>>> setValue(_:forKey:), so it needs to be able to detect whether the value is 
>>> Optional and in case it is, either transform the non-nil value to AnyObject 
>>> (String -> NSString, Array -> NSArray, ...). Which is currently really hard 
>>> to achieve: 
>>> 
>>> var obj: IndexPath? = IndexPath()
>>> let anyValue: Any = obj
>>> anyValue.dynamicType /// Optional.Type
>>> 
>>> /// Using only anyValue, determine if it's Optional and retrieve its value 
>>> if 
>>> /// non-nil as AnyObject.
>>> func isOptional(anyValue: Any) -> Bool {
>>>// Error: Cannot downcast from 'Any' (aka 'protocol<>') to a more 
>>>// optional type 'Optional<_>'
>>>return anyValue is Optional
>>>return anyValue as? Optional != nil
>>>...
>>> }
>>> 
>>> Unless there are major reasons why it's not exposed, I'd propose 
>>> introducing a new function isOptional(anyValue: Any) -> Bool, which would 
>>> simply call Builtin.isOptional just like _isOptional does in Builtin.swift. 
>>> (which pretty much is just taking the current _isOptional, removing 
>>> underscore and marking it public).
>>> 
>>> However, this still doesn't help with the issue of retrieving the value of 
>>> the Optional. You now know the value in `anyValue` is Optional, but there 
>>> is no good way to cast it to e.g. Optional. Here we're getting 
>>> into a vicious cycle that Any can be an Optional which is Any.
>>> 
>>> My second part of the proposal introduces another function:
>>> 
>>> func asOptional(anyValue: Any) -> Optional?
>>> 
>>> Which will:
>>> - return nil if !isOptional(anyValue)
>>> - return a non-nil value only if `anyValue` contains in fact an Optional of 
>>> type T.
>>> 
>>> Usage:
>>> 
>>> if let anyObjOptional: AnyObject? = asOptional(anyValue: anyValue) {
>>>if let anyObj = anyObjOptional {
>>>// anyObj is now the actual content of the optional.
>>>}
>>> }
>>> 
>>> As a sidenote, this is my current workaround:
>>> 
>>> private protocol _XUOptional {
>>>var objectValue: AnyObject? { get }
>>> }
>>> 
>>> extension Optional: _XUOptional {
>>>var objectValue: AnyObject? {
>>>switch self {
>>>case .None:
>>>return nil
>>>case .Some(_):
>>>return self! as? AnyObject
>>>}
>>>}
>>> }
>>> 
>>> if let optional = anyValue as? _XUOptional {
>>>let object = optional.objectValue
>>>/// ...
>>> }
>>> 
>>> 
>>> 
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> 
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Re: [swift-evolution] [Pitch] Detecting and working with Optionals from Any

[Charlie Monroe via swift-evolution]

Unfortunately, this is not as easy, because automatic bridging won't be applied:

let myString: String? = "Hello"
let anyValue: Any = myString

myString as? AnyObject // _NSContiguousString
anyValue as? AnyObject // nil, since String is struct

let array: [String]? = ["Hello"]
let anyArray: Any = array
anyArray as? AnyObject // nil
anyArray as? [AnyObject] // nil
array as? AnyObject // ["Hello"]

And this goes for strings, arrays, dictionaries and possibly other types. Which 
means that you need to handle manually all of the bridging to ObjC types, which 
has really grown in Swift 3, taking into account all the Foundation types that 
are now structs.

Should this then be considered compiler bug that bridging isn't taken into 
account?

Nevertheless, I'd still find it useful exposing the isOptional() function as 
well as the asOptional which would allow a cast from Any to Optional which 
is not possible at all at this moment since any such cast will pick up the 
Optional first:

let myString: String? = "Hello"
let anyValue: Any = myString
if let value = anyValue as? Any {
value.dynamicType // This is still Optional, not naively just the 
value of the optional
}



> On Jun 21, 2016, at 8:18 PM, Joe Groff  wrote:
> 
> 'as?' should already do this. If you have an Any that contains an Optional 
> and cast 'any as? T', you'll get the value inside the Optional if there is 
> one, or the cast will fail if the optional is nil or the type doesn't match.
> 
> -Joe
> 
>> On Jun 20, 2016, at 11:00 PM, Charlie Monroe via swift-evolution 
>>  wrote:
>> 
>> I've recently written a CoreData editor on iOS which automatically generates 
>> UI based on the model which is described using classes such as 
>> PrimitiveProperty, etc. Since it automatically sets the value on the entity, 
>> it needs to convert the value to AnyObject in order to pass it to 
>> setValue(_:forKey:), so it needs to be able to detect whether the value is 
>> Optional and in case it is, either transform the non-nil value to AnyObject 
>> (String -> NSString, Array -> NSArray, ...). Which is currently really hard 
>> to achieve: 
>> 
>> var obj: IndexPath? = IndexPath()
>> let anyValue: Any = obj
>> anyValue.dynamicType /// Optional.Type
>> 
>> /// Using only anyValue, determine if it's Optional and retrieve its value 
>> if 
>> /// non-nil as AnyObject.
>> func isOptional(anyValue: Any) -> Bool {
>>// Error: Cannot downcast from 'Any' (aka 'protocol<>') to a more 
>>// optional type 'Optional<_>'
>>return anyValue is Optional
>>return anyValue as? Optional != nil
>>...
>> }
>> 
>> Unless there are major reasons why it's not exposed, I'd propose introducing 
>> a new function isOptional(anyValue: Any) -> Bool, which would simply call 
>> Builtin.isOptional just like _isOptional does in Builtin.swift. (which 
>> pretty much is just taking the current _isOptional, removing underscore and 
>> marking it public).
>> 
>> However, this still doesn't help with the issue of retrieving the value of 
>> the Optional. You now know the value in `anyValue` is Optional, but there is 
>> no good way to cast it to e.g. Optional. Here we're getting into 
>> a vicious cycle that Any can be an Optional which is Any.
>> 
>> My second part of the proposal introduces another function:
>> 
>> func asOptional(anyValue: Any) -> Optional?
>> 
>> Which will:
>> - return nil if !isOptional(anyValue)
>> - return a non-nil value only if `anyValue` contains in fact an Optional of 
>> type T.
>> 
>> Usage:
>> 
>> if let anyObjOptional: AnyObject? = asOptional(anyValue: anyValue) {
>>if let anyObj = anyObjOptional {
>>// anyObj is now the actual content of the optional.
>>}
>> }
>> 
>> As a sidenote, this is my current workaround:
>> 
>> private protocol _XUOptional {
>>var objectValue: AnyObject? { get }
>> }
>> 
>> extension Optional: _XUOptional {
>>var objectValue: AnyObject? {
>>switch self {
>>case .None:
>>return nil
>>case .Some(_):
>>return self! as? AnyObject
>>}
>>}
>> }
>> 
>> if let optional = anyValue as? _XUOptional {
>>let object = optional.objectValue
>>/// ...
>> }
>> 
>> 
>> 
>> ___
>> swift-evolution mailing list
>> swift-evolution@swift.org
>> https://lists.swift.org/mailman/listinfo/swift-evolution
> 

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Re: [swift-evolution] [Pitch] Detecting and working with Optionals from Any

[Joe Groff via swift-evolution]

'as?' should already do this. If you have an Any that contains an Optional 
and cast 'any as? T', you'll get the value inside the Optional if there is one, 
or the cast will fail if the optional is nil or the type doesn't match.

-Joe

> On Jun 20, 2016, at 11:00 PM, Charlie Monroe via swift-evolution 
>  wrote:
> 
> I've recently written a CoreData editor on iOS which automatically generates 
> UI based on the model which is described using classes such as 
> PrimitiveProperty, etc. Since it automatically sets the value on the entity, 
> it needs to convert the value to AnyObject in order to pass it to 
> setValue(_:forKey:), so it needs to be able to detect whether the value is 
> Optional and in case it is, either transform the non-nil value to AnyObject 
> (String -> NSString, Array -> NSArray, ...). Which is currently really hard 
> to achieve: 
> 
> var obj: IndexPath? = IndexPath()
> let anyValue: Any = obj
> anyValue.dynamicType /// Optional.Type
> 
> /// Using only anyValue, determine if it's Optional and retrieve its value if 
> /// non-nil as AnyObject.
> func isOptional(anyValue: Any) -> Bool {
> // Error: Cannot downcast from 'Any' (aka 'protocol<>') to a more 
> // optional type 'Optional<_>'
> return anyValue is Optional
> return anyValue as? Optional != nil
> ...
> }
> 
> Unless there are major reasons why it's not exposed, I'd propose introducing 
> a new function isOptional(anyValue: Any) -> Bool, which would simply call 
> Builtin.isOptional just like _isOptional does in Builtin.swift. (which pretty 
> much is just taking the current _isOptional, removing underscore and marking 
> it public).
> 
> However, this still doesn't help with the issue of retrieving the value of 
> the Optional. You now know the value in `anyValue` is Optional, but there is 
> no good way to cast it to e.g. Optional. Here we're getting into a 
> vicious cycle that Any can be an Optional which is Any.
> 
> My second part of the proposal introduces another function:
> 
> func asOptional(anyValue: Any) -> Optional?
> 
> Which will:
> - return nil if !isOptional(anyValue)
> - return a non-nil value only if `anyValue` contains in fact an Optional of 
> type T.
> 
> Usage:
> 
> if let anyObjOptional: AnyObject? = asOptional(anyValue: anyValue) {
> if let anyObj = anyObjOptional {
> // anyObj is now the actual content of the optional.
> }
> }
> 
> As a sidenote, this is my current workaround:
> 
> private protocol _XUOptional {
> var objectValue: AnyObject? { get }
> }
> 
> extension Optional: _XUOptional {
> var objectValue: AnyObject? {
> switch self {
> case .None:
> return nil
> case .Some(_):
> return self! as? AnyObject
> }
> }
> }
> 
> if let optional = anyValue as? _XUOptional {
> let object = optional.objectValue
> /// ...
> }
> 
> 
> 
> ___
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> swift-evolution@swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution

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[swift-evolution] [Pitch] Detecting and working with Optionals from Any

[Charlie Monroe via swift-evolution]

I've recently written a CoreData editor on iOS which automatically generates UI 
based on the model which is described using classes such as PrimitiveProperty, 
etc. Since it automatically sets the value on the entity, it needs to convert 
the value to AnyObject in order to pass it to setValue(_:forKey:), so it needs 
to be able to detect whether the value is Optional and in case it is, either 
transform the non-nil value to AnyObject (String -> NSString, Array -> NSArray, 
...). Which is currently really hard to achieve: 

var obj: IndexPath? = IndexPath()
let anyValue: Any = obj
anyValue.dynamicType /// Optional.Type

/// Using only anyValue, determine if it's Optional and retrieve its value if 
/// non-nil as AnyObject.
func isOptional(anyValue: Any) -> Bool {
// Error: Cannot downcast from 'Any' (aka 'protocol<>') to a more 
// optional type 'Optional<_>'
return anyValue is Optional
return anyValue as? Optional != nil
...
}

Unless there are major reasons why it's not exposed, I'd propose introducing a 
new function isOptional(anyValue: Any) -> Bool, which would simply call 
Builtin.isOptional just like _isOptional does in Builtin.swift. (which pretty 
much is just taking the current _isOptional, removing underscore and marking it 
public).

However, this still doesn't help with the issue of retrieving the value of the 
Optional. You now know the value in `anyValue` is Optional, but there is no 
good way to cast it to e.g. Optional. Here we're getting into a 
vicious cycle that Any can be an Optional which is Any.

My second part of the proposal introduces another function:

func asOptional(anyValue: Any) -> Optional?

Which will:
- return nil if !isOptional(anyValue)
- return a non-nil value only if `anyValue` contains in fact an Optional of 
type T.

Usage:

if let anyObjOptional: AnyObject? = asOptional(anyValue: anyValue) {
if let anyObj = anyObjOptional {
// anyObj is now the actual content of the optional.
}
}

As a sidenote, this is my current workaround:

private protocol _XUOptional {
var objectValue: AnyObject? { get }
}

extension Optional: _XUOptional {
var objectValue: AnyObject? {
switch self {
case .None:
return nil
case .Some(_):
return self! as? AnyObject
}
}
}

if let optional = anyValue as? _XUOptional {
let object = optional.objectValue
/// ...
}



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