<html><head><style>body{font-family:Helvetica,Arial;font-size:13px}</style></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div id="bloop_customfont" style="margin: 0px;"><blockquote type="cite" class="clean_bq" style="color: rgb(0, 0, 0); font-family: Helvetica, Arial; font-size: 13px;"><div dir="auto">I'm curious to hear what issue your client had with you using many frameworks that static linking doesn't solve.</div></blockquote><div style="color: rgb(0, 0, 0); font-family: Helvetica, Arial; font-size: 13px;"><div dir="auto"><br></div></div><div dir="auto" style="color: rgb(0, 0, 0); font-family: Helvetica, Arial; font-size: 13px;">The issue here is the number of frameworks that the user drags and drops into Xcode. Most libraries ship as a single framework, see<a href="https://www.mapbox.com/ios-sdk/"> this page</a> for a typical example of what the installation documentation for this process generally looks like.</div><div dir="auto" style="color: rgb(0, 0, 0); font-family: Helvetica, Arial; font-size: 13px;"><br></div><div dir="auto" style="color: rgb(0, 0, 0); font-family: Helvetica, Arial; font-size: 13px;">From a user POV, there is no difference between dragging 4 frameworks and dragging 4 .a libraries. Actually, the .a case is worse in Swift because in addition to object code (.a) we have .swiftmodule, .swiftdoc, and .modulemap. So that's a lot of files to drag.</div><div dir="auto" style="color: rgb(0, 0, 0); font-family: Helvetica, Arial; font-size: 13px;"><br></div><div dir="auto" style="color: rgb(0, 0, 0); font-family: Helvetica, Arial; font-size: 13px;">I have been involved in generating solutions for this problem in other areas (see the <a href="http://anarchytools.org/docs/atbin.html">atbin standard</a> for example) but none of them are supported by Xcode.</div><div dir="auto" style="color: rgb(0, 0, 0); font-family: Helvetica, Arial; font-size: 13px;"><br></div><div dir="auto" style="color: rgb(0, 0, 0); font-family: Helvetica, Arial; font-size: 13px;">Finally, static linking has nothing to do with visibility or the problems of exposing these frameworks as public API.</div><div dir="auto" style="color: rgb(0, 0, 0); font-family: Helvetica, Arial; font-size: 13px;"><br></div><div dir="auto"><blockquote type="cite" style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; padding-left: 5px; border-left-width: 1px !important; border-left-color: rgb(0, 64, 128) !important;"><div id="bloop_customfont" style="margin: 0px;"><div dir="auto">I don't see why submodules could not profit from WMO: the module is still compiled all together. Submodules are simply a scoping/hiding mechanism.</div></div><div id="bloop_sign_1490300347339394048" class="bloop_sign"></div></blockquote><br></div><div dir="auto">Then you will be surprised to hear that this is a subject of some debate. <a href="https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160620/021749.html">Relevant thread.</a></div><div dir="auto"><br></div><div dir="auto"><blockquote type="cite" style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; padding-left: 5px; border-left-width: 1px !important; border-left-color: rgb(0, 64, 128) !important;">That looks like a very corner case. I haven't yet found myself in the case where I needed multiple versions of a code base in a same product (binary, framework, application)</blockquote></div><div dir="auto"><br></div><div dir="auto">There are <a href="http://stackoverflow.com/search?q=duplicate+symbols">253 pages</a> of search results for "duplicate symbol" on StackOverflow. Compare with <a href="http://stackoverflow.com/search?q=fileprivate">48 pages</a> on fileprivate. It is quite clear which is the more complicated feature.</div><div dir="auto"><br></div><div dir="auto"><blockquote type="cite" style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; padding-left: 5px; border-left-width: 1px !important; border-left-color: rgb(0, 64, 128) !important;"><div dir="auto">It would be very strange to me if they were independent libraries: what would different them from modules then?</div></blockquote><div><div dir="auto"><br></div></div><div dir="auto">The organization of object code on the filesystem does not necessarily have any relationship to "submodules the philosophical construct".</div><div dir="auto"><br></div><div dir="auto"><blockquote type="cite" style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; padding-left: 5px; border-left-width: 1px !important; border-left-color: rgb(0, 64, 128) !important;">But at the same time, we can't write and review proposals with no regard for future proposals coming down the road or we end up with a clunky language.</blockquote></div><div dir="auto"><br></div><div dir="auto">I'm not aware of evidence any submodule proposal is actually coming. For example <a href="https://github.com/apple/swift/blob/master/docs/Modules.rst#id3">here</a> is the only authoritative statement of the feature, "slated" for Swift 1.0 😆, a giant warning that we do not even have a design, and the doc mostly consists of questions for how the feature should work.</div><div dir="auto"><br></div><div dir="auto">A scoped access modifier on the other hand is a feature that was designed, is implemented, and is now widely used. What you are suggesting is we should throw it away because at any moment a bird could appear in the bush.</div><div dir="auto"><br></div><div dir="auto">But we've waited for that bird for 3 releases. Rather, if that bird were to appear, we could then study whether or not it solves all the problems of the bird in our hand, or whether it does not. But that hypothetical is quite far from the present circumstance.</div></div></div><p class="airmail_on">On March 23, 2017 at 2:02:25 PM, David Hart (<a href="mailto:david@hartbit.com">david@hartbit.com</a>) wrote:</p> <blockquote type="cite" class="clean_bq"><span><div dir="auto"><div></div><div>
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On 23 Mar 2017, at 16:49, Drew Crawford <<a href="mailto:drew@sealedabstract.com">drew@sealedabstract.com</a>>
wrote:<br>
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<p class="airmail_on">On March 23, 2017 at 2:22:20 AM, David Hart
(<a href="mailto:david@hartbit.com">david@hartbit.com</a>)
wrote:</p>
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> We will get static linking at some point in the near
future.</span></span></div>
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<p>Static linking does not fix this issue. Just change "framework"
to ".a".</p>
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<div>I'm curious to hear what issue your client had with you using
many frameworks that static linking doesn't solve.</div>
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> If we wait until we get submodules, we won't be able to
revisit. This is probably our last chance to "remove" a feature.
Submodules can always add features down the way.</blockquote>
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<p>Maybe submodules will solve this issue, maybe not. But
submodules are *much* more complex than scoped access:</p>
<p>* Performance. This is hot code we compile with WMO.
Moving it into a submodule could reduce visibility for
optimization in a way that causes a performance regression.
In particular, we know that specialization of T is a
performance requirement, it isn't clear whether that would be
preserved. Does WMO provide the same visibility across
submodules? Nobody knows.</p>
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<div>I don't see why submodules could not profit from WMO: the
module is still compiled all together. Submodules are simply a
scoping/hiding mechanism.</div>
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<p>* Namespacing. It's possible that one program may ship 3-4
versions of this code because each dependency has a slightly
different version under our current samizdat process. It is
not clear whether submodules would avoid the "duplicate symbols"
issue from C/ObjC. Xiaodi seems quite concerned about a
related "duplicate functions" problem involved with private today,
doubling down on that is not a good idea.</p>
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<div>That looks like a very corner case. I haven't yet found myself
in the case where I needed multiple versions of a code base in a
same product (binary, framework, application)</div>
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<p>* It is not clear whether submodules are from an objectcode
point of view merged into the parent library or kept as individual
libraries</p>
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<div>It would be very strange to me if they were independent
libraries: what would different them from modules then? No other
language I've used works that way.</div>
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<p>* It is not clear from a .swiftmodule point of view whether
submodules are merged into the parent module or distributed as
.swiftmodules / .swiftdocs</p>
<p>* Not clear how much ABI impact there is from submodules at a
time when we are supposed to be trying to stabilize it</p>
<p>I would love to believe that a proposal on submodules will come
through having solutions to all these issues and many more, then we
will implement it and all sing kumbayah. But we are a long
distance from that, and it may never happen at all, certainly we
cannot evaluate proposals that haven't been written.
Meanwhile we have a solution in the hand.</p>
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<div>But at the same time, we can't write and review proposals with
no regard for future proposals coming down the road or we end up
with a clunky language.</div>
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