<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Feb 13, 2017, at 10:14 AM, Adrian Zubarev via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><p style="margin: 15px 0px; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);" class="">Is that assumption correct?</p><pre style="margin: 15px 0px; font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); border: 1px solid rgb(204, 204, 204); overflow: auto; padding: 4px 8px; word-break: normal; word-wrap: normal; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><code class="swift" style="font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); color: inherit; border: 0px; margin: 0px; padding: 0px; word-break: normal; word-wrap: normal;">// Module A
public protocol SQLiteValue {
init(statement: SQLiteStatement, columnAt index: Int) throws
func bind(to statement: SQLiteStatement, at index: Int) throws
}
// Module B
protocol SQLiteLoggable : SQLiteValue {
var logDescription: String { get }
}
</code></pre><p style="margin: 15px 0px; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);" class="">I could not follow your example there. If<span class="Apple-converted-space"> </span><code style="font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); color: inherit; border: 1px solid rgb(234, 234, 234); margin: 0px 2px; padding: 0px 5px; word-break: normal; word-wrap: normal;" class="">SQLiteLoggable</code><span class="Apple-converted-space"> </span>is from module<span class="Apple-converted-space"> </span><code style="font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); color: inherit; border: 1px solid rgb(234, 234, 234); margin: 0px 2px; padding: 0px 5px; word-break: normal; word-wrap: normal;" class="">B</code><span class="Apple-converted-space"> </span>than this should be an error in my opinion. </p></div></blockquote><div>Yes, Brent was using `public protocol` with the same semantics that `public class` has today (i.e. not open) so this would be an error.</div><br class=""><blockquote type="cite" class=""><div class=""><p style="margin: 15px 0px; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);" class="">Otherwise<span class="Apple-converted-space"> </span><code style="font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); color: inherit; border: 1px solid rgb(234, 234, 234); margin: 0px 2px; padding: 0px 5px; word-break: normal; word-wrap: normal;" class="">open</code><span class="Apple-converted-space"> </span>would have less meaning on protocols, because you always could create an empty protocol that has a super<span class="Apple-converted-space"> </span><code style="font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); color: inherit; border: 1px solid rgb(234, 234, 234); margin: 0px 2px; padding: 0px 5px; word-break: normal; word-wrap: normal;" class="">public protocol</code><span class="Apple-converted-space"> </span>which you’re not allowed to conform to in module B. This would be a silly workaround to being able to conform to it<span class="Apple-converted-space"> </span><code style="font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); color: inherit; border: 1px solid rgb(234, 234, 234); margin: 0px 2px; padding: 0px 5px; word-break: normal; word-wrap: normal;" class="">SQLiteValue</code><span class="Apple-converted-space"> </span>indirectly without any further requirement like in<span class="Apple-converted-space"> </span><code style="font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); color: inherit; border: 1px solid rgb(234, 234, 234); margin: 0px 2px; padding: 0px 5px; word-break: normal; word-wrap: normal;" class="">SQLiteValueConvertible</code>.</p><p style="margin: 15px 0px; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);" class="">That said, it makes no sense to me to allow that, because it’s simply a workaround to conform to a protocol which<span class="Apple-converted-space"> </span><code style="font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); color: inherit; border: 1px solid rgb(234, 234, 234); margin: 0px 2px; padding: 0px 5px; word-break: normal; word-wrap: normal;" class="">public-but-not-open</code><span class="Apple-converted-space"> </span>tries to prevent.</p><pre style="margin: 15px 0px; font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); border: 1px solid rgb(204, 204, 204); overflow: auto; padding: 4px 8px; word-break: normal; word-wrap: normal; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><code class="swift" style="font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); color: inherit; border: 0px; margin: 0px; padding: 0px; word-break: normal; word-wrap: normal;">// Module X
public protocol A {}
open protocol AA : A { func foo() } // Fine
// Module Y
struct B : A {} // Error
struct B : AA { func foo() { .. } } // Okay
</code></pre></div></blockquote><div>No, `struct B : AA` is an error because in order to conform to `AA`, `B` must also conform to `A`, which it cannot because `A` is closed.</div><div><br class=""></div><br class=""><blockquote type="cite" class=""><div class=""><pre style="margin: 15px 0px; font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); border: 1px solid rgb(204, 204, 204); overflow: auto; padding: 4px 8px; word-break: normal; word-wrap: normal; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><code class="swift" style="font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); color: inherit; border: 0px; margin: 0px; padding: 0px; word-break: normal; word-wrap: normal;">
protocol C : A {} // Error because `struct B : C` would equal `struct B : A`
</code></pre></div></blockquote><div>No, this is allowed. However the only types that can conform to `C` are types declared in module X that *already* conform to `A`. They may be extended to retroactively conform to `C`.</div><br class=""><blockquote type="cite" class=""><div class=""><pre style="margin: 15px 0px; font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); border: 1px solid rgb(204, 204, 204); overflow: auto; padding: 4px 8px; word-break: normal; word-wrap: normal; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><code class="swift" style="font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); color: inherit; border: 0px; margin: 0px; padding: 0px; word-break: normal; word-wrap: normal;">protocol CC : AA {} // Should work even empty, because we have more requirement from `AA`
</code></pre><p style="margin: 15px 0px; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);" class=""><code style="font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); color: inherit; border: 1px solid rgb(234, 234, 234); margin: 0px 2px; padding: 0px 5px; word-break: normal; word-wrap: normal;" class="">public</code><span class="Apple-converted-space"> </span>should have a consistent meaning across all types from module A in module B, which is ‘not allowed to sub-type from’ and in case of protocols additionally ‘not allowed to conform to’.</p><span style="font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254); float: none; display: inline !important;" class="">_______________________________________________</span><br style="font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);" class=""><span style="font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254); float: none; display: inline !important;" class="">swift-evolution mailing list</span><br style="font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);" class=""><a href="mailto:swift-evolution@swift.org" style="color: rgb(65, 131, 196); background-color: rgb(254, 254, 254); text-decoration: none; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">swift-evolution@swift.org</a><br style="font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);" class=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" style="color: rgb(65, 131, 196); background-color: rgb(254, 254, 254); text-decoration: none; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br style="font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);" class=""></div></blockquote></div><br class=""></body></html>