> On Dec 3, 2017, at 2:44 PM, Xiaodi Wu <xiaodi...@gmail.com> wrote:
>> and you don’t realize that PyVal’s are involved.  However, if you are 
>> actively writing the code, you have access to code completion and other 
>> things that tell you these types, and if it is important for the clarity of 
>> the code, you write this instead:
>>      let x :PyVal = foo()[“someKey”]
>> There is nothing specific to this proposal about this issue.
> See above.  In the case of PyVal specifically the concern is somewhat 
> mitigated by the name of the type.  That won’t necessarily always be the case.
> If that's the concern, then it would be pretty straightforward to restrict 
> dynamic protocols for stdlib internal use only and expose only PyVal. The 
> trade-off is that all such bridging code would have to be shipped with Swift 
> itself.

Right, this is specifically mentioned as option #2 in the proposal:

It sounds like Matthew’s concerns can be addressed by him +1’ing that 
alternative when it comes up for review.

>> You miss my point.  My point is that AnyObject lookup was carefully 
>> considered, has stood the test of time, and is the *right* answer.  Swift 1 
>> would not have been nearly as successful without it.
> I don’t think I do.  I was trying to agree with exactly the point that it was 
> the right answer in the early days of Swift and getting it right then was 
> essential to Swift’s success.  

Ok, but the “early days of Swift” are directly analogous to the present days of 
other dynamic languages.  

> Aside from the historical necessity of AnyObject, it is also a very specific 
> and widely know type that doesn’t have any statically available members at 
> all and only looks up @objc members.  These properties help to reduce the 
> risk that somebody misunderstands what is going on.
> I imagine we could restrict all such dynamic types from having any statically 
> available members without losing much.

This isn’t practical.  We need some traditionally defined members so that PyVal 
can conform to standard protocols, like ExpressibleByIntegerLiteral and many 


swift-evolution mailing list

Reply via email to