[swift-users] extension Dictionary where Key == MyStructType

[Darren Mo]

Wait but then I can’t use Dictionary methods inside of DictionaryType, right?

> On Jan 27, 2016, at 4:24 PM, Dmitri Gribenko <gribozavr at gmail.com> wrote:
> 
> On Wed, Jan 27, 2016 at 12:16 PM, Darren Mo via swift-users
> <swift-users at swift.org> wrote:
>> I want to add a method to Dictionary but only if the key is a specific
>> non-protocol type.
>> 
>> I tried:
>> extension Dictionary where Key == MyStructType
>> 
>> This yields “error: same-type requirement makes generic parameter 'Key'
>> non-generic”.
>> 
>> Is there a way to do this that doesn’t involve subclassing Dictionary?
> 
> There is a workaround that involves adding an otherwise a useless
> protocol.   I leave it up to you to decide whether it is worth it.
> 
> protocol DictionaryType {
>  typealias Key
>  typealias Value
> }
> 
> extension Dictionary : DictionaryType {}
> 
> extension DictionaryType where Key == MyStructType { ... }
> 
> Dmitri
> 
> -- 
> main(i,j){for(i=2;;i++){for(j=2;j<i;j++){if(!(i%j)){j=0;break;}}if
> (j){printf("%d\n",i);}}} /*Dmitri Gribenko <gribozavr at gmail.com>*/