[swift-evolution] Compiler Warning on Unextended Classes

[Kevin Lundberg]

It seems to me that such a linter would need to scan the entire module
to determine if a class is subclassed, provided that it is internal. My
understanding of linters is that they typically don't do static analysis
of this sort, they are more targeted at local source or AST analysis.
Whole module optimization already looks at if an internal class is
subclassed in order to do its work, so presumably the same sort of
analysis would be required which suggests a compiler feature as I
understand it.


On 6/16/2016 4:32 PM, Saagar Jha via swift-evolution wrote:
> I think that linters are the best way to handle this. It’s not really
> a code smell that should always be taken care of (which would indicate
> that the compiler should warn about it), and as such should be
> relegated to the linter.
>
> On Thu, Jun 16, 2016 at 10:08 AM Rehat Kathuria via swift-evolution
> <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>
>     Agree with Sean that this shouldn’t apply to classes declared
>     public; I also don’t think the "default by final” discussion ever
>     came to a consensus.
>
>     As for linters, my understanding of them is that they’re inclined
>     to style-guides as opposed to architectural suggestions.The
>     declaration of a class being final isn’t one that’s dependant on
>     style, rather architecture.
>
>
>>     On 16 Jun 2016, at 17:57, Xiaodi Wu <xiaodi.wu at gmail.com
>>     <mailto:xiaodi.wu at gmail.com>> wrote:
>>
>>     On Thu, Jun 16, 2016 at 11:39 AM, L. Mihalkovic via
>>     swift-evolution <swift-evolution at swift.org
>>     <mailto:swift-evolution at swift.org>> wrote:
>>
>>         Likely a lint level feature, no?
>>
>>
>>     Agreed. Sounds like a linter feature. 
>>      
>>
>>         > On Jun 16, 2016, at 6:27 PM, Sean Heber via swift-evolution
>>         <swift-evolution at swift.org
>>         <mailto:swift-evolution at swift.org>> wrote:
>>         >
>>         > I would think this would not apply to public classes.
>>         >
>>         > There has also been discussion in the past about making
>>         final the default - I don’t remember if that ever resolved
>>         into some kind of consensus or not, though.
>>         >
>>         > l8r
>>         > Sean
>>         >
>>         >
>>         >> On Jun 16, 2016, at 11:23 AM, Saagar Jha via
>>         swift-evolution <swift-evolution at swift.org
>>         <mailto:swift-evolution at swift.org>> wrote:
>>         >>
>>         >> Correct me if I’m wrong, but if you’re writing some kind
>>         of framework and your class is not final but never
>>         subclassed, you wouldn’t want the warning, even if you’d like
>>         to allow users to subclass it?
>>         >>
>>         >>
>>         >>
>>         >> On Thu, Jun 16, 2016 at 9:02 AM Rehat Kathuria via
>>         swift-evolution <swift-evolution at swift.org
>>         <mailto:swift-evolution at swift.org>> wrote:
>>         >> I’d like the compiler to present a warning when a class
>>         not declared as final is never subclassed. Thoughts?
>>         >> _______________________________________________
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>>         >> --
>>         >> -Saagar Jha
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>>         >
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>>
>
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> -- 
> -Saagar Jha
>
>
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