[Pitch] Detecting and working with Optionals from Any


(Charlie Monroe) #1

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<Foundation.IndexPath>.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<AnyObject>. 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<T>(anyValue: Any) -> Optional<T>?

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
    /// ...
}


(Joe Groff) #2

'as?' should already do this. If you have an Any that contains an Optional<T> 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 <swift-evolution@swift.org> 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<Foundation.IndexPath>.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<AnyObject>. 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<T>(anyValue: Any) -> Optional<T>?

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


(Charlie Monroe) #3

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<Any> 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<String>, not naively just the value of the optional
}

···

On Jun 21, 2016, at 8:18 PM, Joe Groff <jgroff@apple.com> wrote:

'as?' should already do this. If you have an Any that contains an Optional<T> 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 <swift-evolution@swift.org> 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<Foundation.IndexPath>.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<AnyObject>. 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<T>(anyValue: Any) -> Optional<T>?

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


(Joe Groff) #4

I'd call that a bug, not something requiring evolution discussion. We're trying to phase this behavior out of dynamic casts, though (see https://github.com/apple/swift-evolution/blob/master/proposals/0083-remove-bridging-from-dynamic-casts.md).

-Joe

···

On Jun 21, 2016, at 10:11 PM, Charlie Monroe <charlie@charliemonroe.net> 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.


(L Mihalkovic) #5

Func asOpt<T>(v:Any) -> Optional<T> {
  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 <swift-evolution@swift.org> 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<Any> 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<String>, not naively just the value of the optional
}

On Jun 21, 2016, at 8:18 PM, Joe Groff <jgroff@apple.com> wrote:

'as?' should already do this. If you have an Any that contains an Optional<T> 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 <swift-evolution@swift.org> 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<Foundation.IndexPath>.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<AnyObject>. 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<T>(anyValue: Any) -> Optional<T>?

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

_______________________________________________
swift-evolution mailing list
swift-evolution@swift.org
https://lists.swift.org/mailman/listinfo/swift-evolution


(John McCall) #6

Func asOpt<T>(v:Any) -> Optional<T> {
  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 12:15 AM, L. Mihalkovic via swift-evolution <swift-evolution@swift.org> wrote:

On Jun 22, 2016, at 7:11 AM, Charlie Monroe via swift-evolution <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> 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<Any> 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<String>, not naively just the value of the optional
}

On Jun 21, 2016, at 8:18 PM, Joe Groff <jgroff@apple.com <mailto:jgroff@apple.com>> wrote:

'as?' should already do this. If you have an Any that contains an Optional<T> 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 <swift-evolution@swift.org <mailto:evolution@swift.org>> 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<Foundation.IndexPath>.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<AnyObject>. 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<T>(anyValue: Any) -> Optional<T>?

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 <mailto:swift-evolution@swift.org>
https://lists.swift.org/mailman/listinfo/swift-evolution

_______________________________________________
swift-evolution mailing list
swift-evolution@swift.org <mailto:swift-evolution@swift.org>
https://lists.swift.org/mailman/listinfo/swift-evolution

_______________________________________________
swift-evolution mailing list
swift-evolution@swift.org
https://lists.swift.org/mailman/listinfo/swift-evolution


(L Mihalkovic) #7

Ext Optional {
Func ifUnwraps<T>(_ 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 <laurent.mihalkovic@gmail.com> wrote:

Func asOpt<T>(v:Any) -> Optional<T> {
  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 <swift-evolution@swift.org> 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<Any> 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<String>, not naively just the value of the optional
}

On Jun 21, 2016, at 8:18 PM, Joe Groff <jgroff@apple.com> wrote:

'as?' should already do this. If you have an Any that contains an Optional<T> 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 <swift-evolution@swift.org> 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<Foundation.IndexPath>.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<AnyObject>. 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<T>(anyValue: Any) -> Optional<T>?

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

_______________________________________________
swift-evolution mailing list
swift-evolution@swift.org
https://lists.swift.org/mailman/listinfo/swift-evolution


(Charlie Monroe) #8

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 <laurent.mihalkovic@gmail.com> wrote:

Func asOpt<T>(v:Any) -> Optional<T> {
  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 <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> 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<Any> 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<String>, not naively just the value of the optional
}

On Jun 21, 2016, at 8:18 PM, Joe Groff <jgroff@apple.com <mailto:jgroff@apple.com>> wrote:

'as?' should already do this. If you have an Any that contains an Optional<T> 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 <swift-evolution@swift.org <mailto:evolution@swift.org>> 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<Foundation.IndexPath>.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<AnyObject>. 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<T>(anyValue: Any) -> Optional<T>?

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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(L Mihalkovic) #9

Func asOpt<T>(v:Any) -> Optional<T> {
  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)

···

On Jun 22, 2016, at 5:51 PM, John McCall <rjmccall@apple.com> wrote:

On Jun 22, 2016, at 12:15 AM, L. Mihalkovic via swift-evolution <swift-evolution@swift.org> wrote:

John.

On Jun 22, 2016, at 7:11 AM, Charlie Monroe via swift-evolution <swift-evolution@swift.org> 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<Any> 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<String>, not naively just the value of the optional
}

On Jun 21, 2016, at 8:18 PM, Joe Groff <jgroff@apple.com> wrote:

'as?' should already do this. If you have an Any that contains an Optional<T> 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 <swift-evolution@swift.org> 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<Foundation.IndexPath>.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<AnyObject>. 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<T>(anyValue: Any) -> Optional<T>?

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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https://lists.swift.org/mailman/listinfo/swift-evolution

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swift-evolution@swift.org
https://lists.swift.org/mailman/listinfo/swift-evolution

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https://lists.swift.org/mailman/listinfo/swift-evolution


(Charlie Monroe) #10

I'd call that a bug, not something requiring evolution discussion. We're trying to phase this behavior out of dynamic casts, though (see https://github.com/apple/swift-evolution/blob/master/proposals/0083-remove-bridging-from-dynamic-casts.md).

Ok, I've filed a bug report.

My suggestion to expose the Builtin.isOptional function though still stands since it may be of some use nevertheless.

···

-Joe


(Charlie Monroe) #11

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>, 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<AnyObject>
    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?

···

On Jun 22, 2016, at 5:59 PM, L. Mihalkovic <laurent.mihalkovic@gmail.com> wrote:

On Jun 22, 2016, at 5:51 PM, John McCall <rjmccall@apple.com <mailto:rjmccall@apple.com>> wrote:

On Jun 22, 2016, at 12:15 AM, L. Mihalkovic via swift-evolution <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote:

Func asOpt<T>(v:Any) -> Optional<T> {
  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 <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> 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<Any> 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<String>, not naively just the value of the optional
}

On Jun 21, 2016, at 8:18 PM, Joe Groff <jgroff@apple.com <mailto:jgroff@apple.com>> wrote:

'as?' should already do this. If you have an Any that contains an Optional<T> 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 <swift-evolution@swift.org <mailto:evolution@swift.org>> 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<Foundation.IndexPath>.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<AnyObject>. 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<T>(anyValue: Any) -> Optional<T>?

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 <mailto:swift-evolution@swift.org>
https://lists.swift.org/mailman/listinfo/swift-evolution

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swift-evolution@swift.org <mailto:swift-evolution@swift.org>
https://lists.swift.org/mailman/listinfo/swift-evolution

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swift-evolution@swift.org <mailto:swift-evolution@swift.org>
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(Joe Groff) #12

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>, 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<AnyObject>
    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?

A bug.

-Joe

···

On Jun 22, 2016, at 9:12 AM, Charlie Monroe via swift-evolution <swift-evolution@swift.org> wrote:

On Jun 22, 2016, at 5:59 PM, L.Mihalkovic <laurent.mihalkovic@gmail.com> wrote:

On Jun 22, 2016, at 5:51 PM, John McCall <rjmccall@apple.com> wrote:

On Jun 22, 2016, at 12:15 AM, L. Mihalkovic via swift-evolution <swift-evolution@swift.org> wrote:

Func asOpt<T>(v:Any) -> Optional<T> {
  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 <swift-evolution@swift.org> 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<Any> 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<String>, not naively just the value of the optional
}

On Jun 21, 2016, at 8:18 PM, Joe Groff <jgroff@apple.com> wrote:

'as?' should already do this. If you have an Any that contains an Optional<T> 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 <swift-evolution@swift.org> 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<Foundation.IndexPath>.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<AnyObject>. 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<T>(anyValue: Any) -> Optional<T>?

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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https://lists.swift.org/mailman/listinfo/swift-evolution

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swift-evolution@swift.org
https://lists.swift.org/mailman/listinfo/swift-evolution

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https://lists.swift.org/mailman/listinfo/swift-evolution


(John McCall) #13

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>, 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<AnyObject>
    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 9:12 AM, Charlie Monroe <charlie@charliemonroe.net> wrote:

On Jun 22, 2016, at 5:59 PM, L. Mihalkovic <laurent.mihalkovic@gmail.com <mailto:laurent.mihalkovic@gmail.com>> wrote:

On Jun 22, 2016, at 5:51 PM, John McCall <rjmccall@apple.com <mailto:rjmccall@apple.com>> wrote:

On Jun 22, 2016, at 12:15 AM, L. Mihalkovic via swift-evolution <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote:

Func asOpt<T>(v:Any) -> Optional<T> {
  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 <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> 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<Any> 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<String>, not naively just the value of the optional
}

On Jun 21, 2016, at 8:18 PM, Joe Groff <jgroff@apple.com <mailto:jgroff@apple.com>> wrote:

'as?' should already do this. If you have an Any that contains an Optional<T> 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 <swift-evolution@swift.org <mailto:evolution@swift.org>> 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<Foundation.IndexPath>.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<AnyObject>. 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<T>(anyValue: Any) -> Optional<T>?

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 <mailto:swift-evolution@swift.org>
https://lists.swift.org/mailman/listinfo/swift-evolution

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swift-evolution@swift.org <mailto:swift-evolution@swift.org>
https://lists.swift.org/mailman/listinfo/swift-evolution

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