> On Sep 11, 2016, at 6:12 PM, Tanner Nelson via swift-users
> <swift-users@swift.org> wrote:
>
> Hey Swift Users,
>
> I was wondering how you all work around not being able to add stored
> properties in extensions (especially protocol extensions).
>
> I ran into an issue recently where I needed an internal stored variable for a
> protocol, but I didn't want the conformer to worry about implementing the
> variable.
>
> I ended up using something like this to achieve the effect.
>
> extension MyProtocol {
> private var address: String {
> mutating get {
> var id = ""
> withUnsafePointer(to: &self) { id = "\($0)"}
> return id
BTW, you can write `return withUnsafePointer(to: &self) { "\($0)" }` instead.
> }
> }
>
> var myStoredVar: Bool {
> mutating get {
> return _storage[address] ?? false
> }
> set {
> _storage[address] = newValue
> }
> }
> }
>
> Obviously not ideal, but I don't see another way to achieve this besides
> subclassing (which has its own problems for my situation).
>
> Wondering if anyone has run into this and come up with a better solution or
> other type of work around.
I don't have a better answer to this part.
This particular solution only works if it is ok for `_storage[address]` to
potentially be reused by a new instance, though (if the old instance is
deallocated and the new one is allocated in its place).
- Daniel
>
> Thanks!
> Tanner
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