> On Nov 28, 2017, at 3:18 PM, Slava Pestov <spes...@apple.com> wrote:
>
>
>
>> On Nov 28, 2017, at 8:44 AM, Matthew Johnson <matt...@anandabits.com
>> <mailto:matt...@anandabits.com>> wrote:
>>
>> func makeResource(
>> with configuration: Configuration = () where Configuration == Void,
>> actionHandler: @escaping (Action) -> Void = { _ in } where Action ==
>> Never
>> )
>
> Similar question to the one I posed earlier — what happens if I’m using
> makeResource() from a generic context? Is the conditional default argument
> simply not available?
Right. If the constraints are not met at the call site the default is not
available. I think you understood, but looking at the example above I omitted
the resource type parameter. It should read:
func makeResource<R: Resource>(
with configuration: R.Configuration = () where R.Configuration == Void,
actionHandler: @escaping (R.Action) -> Void = { _ in } where R.Action ==
Never
)
>
> In this case, how is it different from defining some static overloads of
> makeResource(), some of which have default arguments and some of which are
> generic?
>From the point of view of the call site it is not different. The differences
>are that:
* the user is presented with a single API rather than several overloads
* the library author isn’t required to maintain an overload set
* the compiler doesn’t have to reason about an overload set which might improve
build times, etc
>
> Slava
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