[swift-evolution] access control

David Owens II david at owensd.io
Mon Jan 25 11:09:38 CST 2016

> On Jan 25, 2016, at 4:47 AM, Ilya Belenkiy via swift-evolution <swift-evolution at swift.org> wrote:
>> Data encapsulation is indeed one of the cornerstone of OO, but every design decision is a trade-off. Is Python not object-oriented because they lack a private keyword, and have the convention of marking internal items with a leading underscore?
> Then Python has the same problem. A language that *supports* OOP should not leave such an important part of OOP to coding by convention. 

I think this where you are being lead astray. A language does not need to have strict access controls in order to be considered OO. Languages like C#, Java, and to some extent, C++ tend to make people think this. You don’t even need “classes” to do OO either.

>> The best anyone can do is make the breaking of encapsulation an explicit choice. I’m intuiting that you think that writing code into the file where the class was defined is not explicit enough.
> Right now, it’s impossible to make the distinction: is something truly private or can be used safely in the same file? The language has no way of expressing it. The class internal state is not encapsulated outside the bounds of the class.

This really seems like an academic problem vs a pragmatic problem. There’s also no concept of “friend” in Swift either, which is another construct that would have be invented to allow the “private” things to be used by others elsewhere. 


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