[swift-evolution] [Pitch] separate syntax of class inheritance and protocol conformance

[Brandon Knope]

I understand. 

But why would you need to know if it's a class or a protocol to use the type? What understanding comes from knowing this information?

I am honestly trying to understand the problem here and it feels like I'm overlooking something.

Brandon 

> On Jul 22, 2016, at 10:12 AM, Charlie Monroe <charlie at charliemonroe.net> wrote:
> 
> Coming to someone elses code, it adds an extra effort to understand the declaration. Putting inheritance and conformance separately makes the declaration easier to read. At least for me.
> 
>> On Jul 22, 2016, at 4:05 PM, Brandon Knope <bknope at me.com> wrote:
>> 
>> Honest question: what is actually confusing about the current behavior?
>> 
>> I.E. What is important about knowing whether "DataSource" is a class or a protocol?
>> 
>> I thought the blurred distinction was intentional?
>> 
>> Brandon 
>> 
>>> On Jul 22, 2016, at 9:47 AM, Charlie Monroe via swift-evolution <swift-evolution at swift.org> wrote:
>>> 
>>> I agree that this is an issue. Mostly nowadays when more and more classes in Swift do not have a superclass - it simply looks weird:
>>> 
>>> class MyClass: DataSource
>>> 
>>> One doesn't know whether "DataSource" is a class, protocol, etc. Nevertheless, I do not feel that :: is the answer. I really liked, how ObjC did it (which isn't possible with the generics now - is it?), but what about something like this?
>>> 
>>> class BaseClass [SomeDelegate, OtherDelegate, ProtocolX]
>>> class MyClass: BaseClass [SomeDelegate, OtherDelegate, ProtocolX]
>>> extension MyClass [OtherProtocol]
>>> 
>>> 
>>>> On Jul 22, 2016, at 3:14 PM, Vladimir.S via swift-evolution <swift-evolution at swift.org> wrote:
>>>> 
>>>> I remember that this was discussed, but can't find any decision regarding this.. So, as a last chance, don't we want in Swift 3.0, as big source breaking change, separate class inheritance and protocol conformance in syntax?
>>>> 
>>>> Sorry if there was a decision about this suggestions. Please let know in this case.
>>>> 
>>>> I.e. when I see the following I can't understand if the class inherits from base class and conforms to protocols or just conforms to two protocols:
>>>> 
>>>> class MyClass : First, Second, Third {
>>>> }
>>>> 
>>>> We don't have a rule to name protocols with 'Protocol'/other suffix/prefix, or classes with 'T'/'C' prefix or something like this, so I believe to improve the clarity of code we should separate in syntax inheritance and conformance.
>>>> 
>>>> As I understand we should discuss changes in these areas:
>>>> 
>>>> 1. class inheritance :
>>>> class Child: BaseClass
>>>> 
>>>> 2. class conformance :
>>>> class Child: SomeProtocol1, SomeProtocol2
>>>> 
>>>> 3. class inheritance + conformance :
>>>> class Child: BaseClass, SomeProtocol1, SomeProtocol2
>>>> 
>>>> 4. protocol conformance for structs:
>>>> struct Struct: SomeProtocol1, SomeProtocol2
>>>> 
>>>> 5. protocol inheritance:
>>>> protocol Child: BaseProtocol1, BaseProtocol2
>>>> 
>>>> 
>>>> My suggestions:
>>>> 
>>>> I) separate inheritance with double colon :
>>>> 
>>>> 1. class inheritance :
>>>> class Child:: BaseClass
>>>> 
>>>> 2. class conformance :
>>>> class Child: SomeProtocol1, SomeProtocol2
>>>> 
>>>> 3. class inheritance + conformance :
>>>> class Child:: BaseClass : SomeProtocol1, SomeProtocol2
>>>> 
>>>> 4. protocol conformance for structs:
>>>> struct Struct: SomeProtocol1, SomeProtocol2
>>>> 
>>>> 5. protocol inheritance:
>>>> protocol Child:: BaseProtocol1, BaseProtocol2
>>>> 
>>>> 
>>>> II) in class definition use parenthesis to separate inheritance and conformance :
>>>> 
>>>> 1. class inheritance :
>>>> class Child: BaseClass
>>>> 
>>>> 2. class conformance :
>>>> class Child: (SomeProtocol1, SomeProtocol2)
>>>> 
>>>> 3. class inheritance + conformance :
>>>> class Child: BaseClass (SomeProtocol1, SomeProtocol2)
>>>> 
>>>> 4. protocol conformance for structs:
>>>> struct Struct: SomeProtocol1, SomeProtocol2
>>>> or
>>>> struct Struct: (SomeProtocol1, SomeProtocol2)
>>>> should be discussed
>>>> 
>>>> 5. protocol inheritance:
>>>> protocol Child: BaseProtocol1, BaseProtocol2
>>>> 
>>>> 
>>>> III) special word like 'conforms'
>>>> 
>>>> 1. class inheritance :
>>>> class Child: BaseClass
>>>> 
>>>> 2. class conformance :
>>>> class Child: conforms SomeProtocol1, SomeProtocol2
>>>> or
>>>> class Child conforms SomeProtocol1, SomeProtocol2
>>>> 
>>>> 3. class inheritance + conformance :
>>>> class Child: BaseClass conforms SomeProtocol1, SomeProtocol2
>>>> 
>>>> 4. protocol conformance for structs:
>>>> struct Struct: conforms SomeProtocol1, SomeProtocol2
>>>> or
>>>> struct Struct conforms SomeProtocol1, SomeProtocol2
>>>> 
>>>> 5. protocol inheritance:
>>>> protocol Child: BaseProtocol1, BaseProtocol2
>>>> 
>>>> 
>>>> Thoughts?
>>>> _______________________________________________
>>>> swift-evolution mailing list
>>>> swift-evolution at swift.org
>>>> https://lists.swift.org/mailman/listinfo/swift-evolution
>>> 
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>>> swift-evolution mailing list
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> 
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