[swift-evolution] Making `.self` After `Type` Optional

[Matthew Johnson]

Definitely +1 to removing the .self requirement.

Sent from my iPad

> On May 5, 2016, at 11:34 PM, Joe Groff via swift-evolution <swift-evolution at swift.org> wrote:
> 
> To keep progress going on this, I collected my thoughts from March's discussion into a draft proposal:
> 
> https://github.com/apple/swift-evolution/pull/299
> 
> -Joe
> 
>> On Mar 9, 2016, at 11:23 AM, Tanner Nelson via swift-evolution <swift-evolution at swift.org> wrote:
>> 
>> Hello Swift Evolution members,
>> 
>> I would like to propose making `.self` After a Type optional when referencing Types in expressions.
>> 
>> Currently, to pass a Type to a function or method, it is sometimes required to add `.self` after the Type. This behavior is inconsistent as it is only required if the signature has more than one parameter. 
>> 
>> Here is a demonstration of the current inconsistency. 
>> 
>> ```swift
>> func test<T: Any>(type: T.Type, two: String) {
>>   print(type)
>> }
>> 
>> func test<T: Any>(type: T.Type) {
>>   print(type)
>> }
>> 
>> test(Int.self)
>> test(Int)
>> 
>> test(Int.self, two: "")
>> test(Int, two: "") //Expected member name or constructor call after type name
>>     ^~~
>> ``` 
>> 
>> This has been confirmed as a bug, and the report can be seen here <https://bugs.swift.org/browse/SR-899>.
>> 
>> After a Twitter conversation with Joe Groff on the Swift team (https://twitter.com/jckarter/status/707287663586324481) it is determined that this requirement is due to difficulty disambiguating generics `Foo<T>` vs infix less-than operations `Foo < T`.
>> 
>> I propose to allow Types to be used in expressions without needing to explicitly reference `.self`. The motivation for this is as follows:
>> 
>> - Cleaner API
>> - Consistent requirement is less confusing to developers
>> - Disambiguation challenges should not result in more verbose code unless absolutely necessary
>> 
>> Here are some preliminary ideas for how this could be implemented:
>> 
>> - Require spaces around less than expressions and no spaces around generics
>> - Require spaces around infix operators and no spaces around generics
>> - Remove less than overload for comparing a type
>> - (Your idea here)
>> 
>> A draft of an evolution document that provides more background can be viewed here <https://github.com/apple/swift-evolution/pull/197>. It has been preempted by a need for discussion in this mailing list. 
>> 
>> I am looking forward to hearing your feedback on this proposal.
>> 
>> Thank you,
>> Tanner Nelson
>> http://github.com/tannernelson
>> 
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> 
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