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

[Vladimir.S]

Yes, this could be a solution, but what about just one protocol conformance?

class Child: SomeProtocol
class Child: BaseClass

IMO we still need to separate the definition

.. or

class Child: &SomeProtocol

but I don't believe such could be accepted/allowed.

And, after all, this still changes the syntaxt, so we need to decide if 
this change should be done in Swift 3.0, or after, or never..


On 22.07.2016 16:41, Ian Partridge wrote:
> Now that SE-0095 is accepted, I think it would be a good idea to use
> the infix & operator for specifying protocol conformance as well.
>
> 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
>
> Thanks,
> Ian
>
> On 22 July 2016 at 14:14, 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?
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>> swift-evolution at swift.org
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>
>
>