on Tue Jun 06 2017, Karl Wagner <razielim-AT-gmail.com> wrote:
>> On 7. Jun 2017, at 00:25, Dave Abrahams via swift-users
>> <swift-users@swift.org> wrote:
>>
>>
>> on Wed May 31 2017, Steven Brunwasser <swift-users-AT-swift.org
> <http://swift-users-at-swift.org/>> wrote:
>>
>
>>> Yes, I understand this. I was just wondering if there was a naming
>>> convention I should use to differentiate them.
>>
>> I would try to find something more specific and descriptive than
>> “Container” and “Element” if you think there's a chance they would ever
>> arise as associated types of the same type but with distinct identity.
>>
>> Another possibility, if you think that might be about to happen, is that
>> you're using conformance when you should use aggregation. For example,
>> an Int has everything it needs to be a Sequence and/or Iterator (n to
>> infinity), a Collection (of numbers from zero to its bitWidth), etc.,
>> but *should* it conform to those protocols? IMO probably not. If you
>> find yourself hard pressed to describe what something *is* in a few
>> words, it may be conforming to too many protocols.
>
> Additionally, I find that when a type is representable in multiple
> overlapping ways (where “overlapping” is meant quite broadly), it can
> be good to create wrappers for those conformances.
Jah, that's what I meant to imply, but failed to spell out. Thanks for
clarifying, Karl!
>
>
> For example, you might try:
>
> Struct MyThing {
> }
>
> extension MyThing {
>
> var foo: Foo { return MyThing.FooWrapper(self) }
> var bar: Bar { return MyThing.BarWrapper(self) }
>
> struct FooWrapper: Foo {
> let base: MyThing
> init(_ wrapping: MyThing) { self.base = wrapping }
>
> // Implement ‘Foo’ using data from ‘base’.
> }
> }
>
> let something = MyThing()
>
> takesAFoo(something.foo)
> takesABar(something.bar)
>
> This is analogous to how String is represented — the data is stored once, and
> there are multiple
> Collection conformances which interpret the data in different ways (as
> graphemes, or as a collection
> of non-character-boundary code-units in various encodings).
--
-Dave
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