<div dir="ltr">Some minor points:<div><br></div><div>1. One major reason for wanting control over which targets are exported are so packages can control which parts of their API is supported for external use. This is very important to large projects undergoing active development while also trying to support a well-defined, semantically versioned API.</div><div><br></div><div>2. In keeping with #1, and the design of the Swift language, I think the right default is for a module to be private/unexported. This is basically for the same reasons as `internal` is the default access control modifier in Swift. This also relates to the discussion below.</div><div><br></div><div>3. If we are going to add this via a new Target attribute, I suggest we do so using a `flags` parameter and accompanying enumeration. This will be equally readable, I think, but more extensible over time.</div><div><br></div><div>4. Technically, this proposal is defining two new few features, the public/private exported/imported part and the ability for packages to depend on specific targets. They are related problems, but the proposals (and implementation) are otherwise somewhat orthogonal. I'm fine combining them into one proposal, but if it appears that one part is going to require much more design or discussion than the other (or that the combined discussion is too large) we might consider breaking them up.</div><div><br></div><div>There is a larger thing we need to consider with regard to the public/private part of the proposal, and that is its relation to hypothetical future support for package-level namespaces, whereby I mean Swift language support for a new level of namespace (and accompanying access control support in some form) for an entire Package. There are several reasons I think that we will ultimately need such a thing, the most major of which is the module-name collision problem (two packages that want to use a shared common name for a module) that cannot be resolved by SwiftPM without language support. Since such a feature is purely hypothetical at this point, I don't think we need to block forward progress in SwiftPM on it, but I do think we should discuss the consequences.</div><div><br></div><div>Some examples of how these things might be related:</div><div><br></div><div>1. The choice of `public/private` is probably wrong when viewed as a language feature, since they already having existing meanings and `internal` would be a more accurate name within the context of an individual Package. I think we should include some discussion of the best names if we reuse modifier names, or if there is a good argument for finding alternate names ("exported/unexported"?).</div><div><br></div><div>2. Suppose Swift added support for a `package` namespace and access control modifier. This might make it somewhat awkward if we had tied expectations of what targets in an external dependency were built to a *manifest*-level construct.</div><div><br></div><div>3. We should call out that public/private in this sense ultimately won't have any enforcement by the compiler. If a public target exposes a type declared in a private module implicitly (say via a return value), there won't be any error, even though it breaks the encapsulation this feature would partially be intended to provide. Similarly, nothing will prevent a target from importing a private module from an external dependency if was already a transitive dependency of some other public target.</div><div><br></div><div>It would be good to try and work through some of these issues and lay out pros & cons as well as other strategies we could use to mitigate them. In the short term I think we will need to accept and implement some form of this proposal, so this doesn't mean working out what a full solution would look like, let's just make sure we aren't (unknowingly) painting ourselves into a corner.</div><div><br></div><div> - Daniel</div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Jul 7, 2016 at 6:26 AM, Ankit Agarwal via swift-build-dev <span dir="ltr"><<a href="mailto:swift-build-dev@swift.org" target="_blank">swift-build-dev@swift.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Hi swift packagers,</div><div><br></div><div>I am proposing access control to package targets. </div><div><br></div>Link: <a href="https://github.com/aciidb0mb3r/swift-evolution/blob/swiftpm-module-access-control/proposals/xxxx-swiftpm-target-access-control.md" target="_blank">https://github.com/aciidb0mb3r/swift-evolution/blob/swiftpm-module-access-control/proposals/xxxx-swiftpm-target-access-control.md</a><br clear="all"><div><br></div><div>Feedback appreciated!</div><div><br></div><div><h1 style="font-size:2.25em;margin-right:0px;margin-bottom:16px;margin-left:0px;line-height:1.2;padding-bottom:0.3em;border-bottom-width:1px;border-bottom-style:solid;border-bottom-color:rgb(238,238,238);color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';margin-top:0px!important">SwiftPM Target Access Control</h1><ul style="padding-left:2em;margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px"><li>Proposal: <a href="https://github.com/apple/swift-evolution/blob/master/proposals/xxxx-swiftpm-target-access-control.md" style="background-color:transparent;color:rgb(64,120,192);text-decoration:none" target="_blank">SE-XXXX</a></li><li>Author: <a href="https://github.com/aciidb0mb3r" style="background-color:transparent;color:rgb(64,120,192);text-decoration:none" target="_blank">Ankit Aggarwal</a></li><li>Status: <span>In Discussion</span></li><li>Review manager: TBD</li></ul><h2 style="margin-top:1em;margin-bottom:16px;line-height:1.225;font-size:1.75em;padding-bottom:0.3em;border-bottom-width:1px;border-bottom-style:solid;border-bottom-color:rgb(238,238,238);color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol'"><a href="https://github.com/aciidb0mb3r/swift-evolution/tree/swiftpm-module-access-control#introduction" style="background-color:transparent;color:rgb(64,120,192);text-decoration:none;display:inline-block;padding-right:2px;line-height:1" target="_blank"></a>Introduction</h2><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">This proposal aims to address two issues:</p><ol style="padding-left:2em;margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px"><li><p style="margin-top:16px;margin-bottom:16px">Control over the targets exposed (and built) when a SwiftPM package is used as a dependency.</p></li><li><p style="margin-top:16px;margin-bottom:16px">Import (and build) selected targets of a dependency.</p></li></ol><h2 style="margin-top:1em;margin-bottom:16px;line-height:1.225;font-size:1.75em;padding-bottom:0.3em;border-bottom-width:1px;border-bottom-style:solid;border-bottom-color:rgb(238,238,238);color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol'"><a href="https://github.com/aciidb0mb3r/swift-evolution/tree/swiftpm-module-access-control#motivation" style="background-color:transparent;color:rgb(64,120,192);text-decoration:none;display:inline-block;padding-right:2px;line-height:1" target="_blank"></a>Motivation</h2><h4 style="margin-top:1em;margin-bottom:16px;line-height:1.4;font-size:1.25em;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol'"><a href="https://github.com/aciidb0mb3r/swift-evolution/tree/swiftpm-module-access-control#1-control-over-exposed-targets" style="background-color:transparent;color:rgb(64,120,192);text-decoration:none;display:inline-block;padding-right:2px;line-height:1.2" target="_blank"></a>1. Control over exposed targets:</h4><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">SwiftPM allows multiple targets (or modules) inside a package. Packages usually contain sample usage or example targets which are useful during development or testing of the package but are redundant when the package is used as a dependency. This increases compile time for the user of the package.</p><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">As a concrete example: Vapor has a target called <a href="https://github.com/qutheory/vapor/tree/master/Sources/Development" style="background-color:transparent;color:rgb(64,120,192);text-decoration:none" target="_blank"><code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">Development</code></a>.</p><h4 style="margin-top:1em;margin-bottom:16px;line-height:1.4;font-size:1.25em;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol'"><a href="https://github.com/aciidb0mb3r/swift-evolution/tree/swiftpm-module-access-control#2-import-selected-targets" style="background-color:transparent;color:rgb(64,120,192);text-decoration:none;display:inline-block;padding-right:2px;line-height:1.2" target="_blank"></a>2. Import selected targets:</h4><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">Sometimes user of a package is only interested in few targets of a dependency instead of all the targets. Currently there is no way to state this in <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">Package.swift</code> and all the targets are implicitly built and exposed to the user package.</p><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">For e.g.: I would like to use the targets <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">libc</code>, <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">POSIX</code>, <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">Basic</code> of SwiftPM but don't want other targets to be built or exposed in my package.</p><h2 style="margin-top:1em;margin-bottom:16px;line-height:1.225;font-size:1.75em;padding-bottom:0.3em;border-bottom-width:1px;border-bottom-style:solid;border-bottom-color:rgb(238,238,238);color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol'"><a href="https://github.com/aciidb0mb3r/swift-evolution/tree/swiftpm-module-access-control#proposed-solution" style="background-color:transparent;color:rgb(64,120,192);text-decoration:none;display:inline-block;padding-right:2px;line-height:1" target="_blank"></a>Proposed Solution</h2><h4 style="margin-top:1em;margin-bottom:16px;line-height:1.4;font-size:1.25em;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol'"><a href="https://github.com/aciidb0mb3r/swift-evolution/tree/swiftpm-module-access-control#1-control-over-exposed-targets-1" style="background-color:transparent;color:rgb(64,120,192);text-decoration:none;display:inline-block;padding-right:2px;line-height:1.2" target="_blank"></a>1. Control over exposed targets:</h4><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">I propose that package authors be able mark the targets they don't want to be exposed as <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">private</code> i.e. the <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">private</code>targets will be built when that package is root package but not when the package is used as a dependency.</p><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">To mark a target as <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">private</code> I propose <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">PackageDescription</code>'s <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">Target</code> gains a <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">isPrivate</code> boolean property which defaults to <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">false</code>.</p><h4 style="margin-top:1em;margin-bottom:16px;line-height:1.4;font-size:1.25em;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol'"><a href="https://github.com/aciidb0mb3r/swift-evolution/tree/swiftpm-module-access-control#2-import-selected-targets-1" style="background-color:transparent;color:rgb(64,120,192);text-decoration:none;display:inline-block;padding-right:2px;line-height:1.2" target="_blank"></a>2. Import selected targets:</h4><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">I propose that package user be able to specify the targets they want to import into their package.</p><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">To specify the targets to be import I propose to add an optional string array property <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">targets</code> in <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">PackageDescription</code>'s <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">Package.Dependency</code> which defaults to <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">nil</code> i.e. all targets.</p><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">Instead of an optional string array property an enum can also be used:</p><div style="margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px"><pre style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;margin-top:0px;margin-bottom:0px;line-height:1.45;word-wrap:normal;padding:16px;overflow:auto;background-color:rgb(247,247,247);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px"><span style="color:rgb(167,29,93)">enum</span> ImportedTargets {
<span style="color:rgb(167,29,93)">case</span> allTargets <span style="color:rgb(150,152,150)">// Import all the targets, default value.</span>
<span style="color:rgb(167,29,93)">case</span> targets([<span style="color:rgb(0,134,179)">String</span>]) <span style="color:rgb(150,152,150)">// Import only these targets.</span>
}</pre></div><h2 style="margin-top:1em;margin-bottom:16px;line-height:1.225;font-size:1.75em;padding-bottom:0.3em;border-bottom-width:1px;border-bottom-style:solid;border-bottom-color:rgb(238,238,238);color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol'"><a href="https://github.com/aciidb0mb3r/swift-evolution/tree/swiftpm-module-access-control#detailed-design" style="background-color:transparent;color:rgb(64,120,192);text-decoration:none;display:inline-block;padding-right:2px;line-height:1" target="_blank"></a>Detailed Design</h2><h4 style="margin-top:1em;margin-bottom:16px;line-height:1.4;font-size:1.25em;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol'"><a href="https://github.com/aciidb0mb3r/swift-evolution/tree/swiftpm-module-access-control#1-control-over-exposed-targets-2" style="background-color:transparent;color:rgb(64,120,192);text-decoration:none;display:inline-block;padding-right:2px;line-height:1.2" target="_blank"></a>1. Control over exposed targets:</h4><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">Consider a package with following structure: </p><pre style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;margin-top:0px;margin-bottom:16px;line-height:1.45;word-wrap:normal;padding:16px;overflow:auto;background-color:rgb(247,247,247);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;color:rgb(51,51,51)"><code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;padding:0px;margin:0px;background-color:transparent;border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;border:0px;display:inline;overflow:visible;line-height:inherit;word-wrap:normal">├── Package.swift
└── Sources
├── FooLibrary
│ └── Foo.swift
└── SampleCLI
└── main.swift
</code></pre><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">The manifest with <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">private</code> target could look like:</p><div style="margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px"><pre style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;margin-top:0px;margin-bottom:0px;line-height:1.45;word-wrap:normal;padding:16px;overflow:auto;background-color:rgb(247,247,247);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px"><span style="color:rgb(167,29,93)">import</span> <span style="color:rgb(0,134,179)">PackageDescription</span>
<span style="color:rgb(167,29,93)">let</span> package <span style="color:rgb(167,29,93)">=</span> Package(
name: <span style="color:rgb(24,54,145)"><span>"</span>FooLibrary<span>"</span></span>,
targets: [
Target(name: <span style="color:rgb(24,54,145)"><span>"</span>FooLibrary<span>"</span></span>),
Target(name: <span style="color:rgb(24,54,145)"><span>"</span>SampleCLI<span>"</span></span>, isPrivate: <span style="color:rgb(0,134,179)">true</span>),
])</pre></div><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">When this package is used as a dependency only <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">FooLibrary</code> is built and is importable.</p><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">Targets can have other targets as dependency inside a package. A <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">private</code> target should only be a dependency to other private targets. For e.g. A manifest like this should result in a build failure.</p><div style="margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px"><pre style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;margin-top:0px;margin-bottom:0px;line-height:1.45;word-wrap:normal;padding:16px;overflow:auto;background-color:rgb(247,247,247);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px"><span style="color:rgb(167,29,93)">import</span> <span style="color:rgb(0,134,179)">PackageDescription</span>
<span style="color:rgb(167,29,93)">let</span> package <span style="color:rgb(167,29,93)">=</span> Package(
name: <span style="color:rgb(24,54,145)"><span>"</span>FooLibrary<span>"</span></span>,
targets: [
Target(name: <span style="color:rgb(24,54,145)"><span>"</span>FooCore<span>"</span></span>, isPrivate: <span style="color:rgb(0,134,179)">true</span>),
Target(name: <span style="color:rgb(24,54,145)"><span>"</span>FooLibrary<span>"</span></span>, dependencies: [<span style="color:rgb(24,54,145)"><span>"</span>FooCore<span>"</span></span>]), <span style="color:rgb(150,152,150)">// Error FooCore is private.</span>
Target(name: <span style="color:rgb(24,54,145)"><span>"</span>SampleCLI<span>"</span></span>, dependencies: [<span style="color:rgb(24,54,145)"><span>"</span>FooCore<span>"</span></span>], isPrivate: <span style="color:rgb(0,134,179)">true</span>), <span style="color:rgb(150,152,150)">// Not an error because SampleCLI is private.</span>
])</pre></div><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">Error: <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">FooCore</code> is a private target, it cannot be a dependency to the public target <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">FooLibrary</code>.</p><h4 style="margin-top:1em;margin-bottom:16px;line-height:1.4;font-size:1.25em;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol'"><a href="https://github.com/aciidb0mb3r/swift-evolution/tree/swiftpm-module-access-control#2-import-selected-targets-2" style="background-color:transparent;color:rgb(64,120,192);text-decoration:none;display:inline-block;padding-right:2px;line-height:1.2" target="_blank"></a>2. Import selected targets:</h4><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">Consider a dependency with following manifest file:</p><div style="margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px"><pre style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;margin-top:0px;margin-bottom:0px;line-height:1.45;word-wrap:normal;padding:16px;overflow:auto;background-color:rgb(247,247,247);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px"><span style="color:rgb(167,29,93)">import</span> <span style="color:rgb(0,134,179)">PackageDescription</span>
<span style="color:rgb(167,29,93)">let</span> package <span style="color:rgb(167,29,93)">=</span> Package(
name: <span style="color:rgb(24,54,145)"><span>"</span>FooLibrary<span>"</span></span>,
targets: [
Target(name: <span style="color:rgb(24,54,145)"><span>"</span>Foo<span>"</span></span>),
Target(name: <span style="color:rgb(24,54,145)"><span>"</span>Bar<span>"</span></span>, dependencies: [<span style="color:rgb(24,54,145)"><span>"</span>Foo<span>"</span></span>]),
Target(name: <span style="color:rgb(24,54,145)"><span>"</span>Baz<span>"</span></span>),
])</pre></div><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">To get only the <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">Bar</code> target from the above package, following manifest could be written:</p><div style="margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px"><pre style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;margin-top:0px;margin-bottom:0px;line-height:1.45;word-wrap:normal;padding:16px;overflow:auto;background-color:rgb(247,247,247);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px"><span style="color:rgb(167,29,93)">import</span> <span style="color:rgb(0,134,179)">PackageDescription</span>
<span style="color:rgb(167,29,93)">let</span> package <span style="color:rgb(167,29,93)">=</span> Package(
name: <span style="color:rgb(24,54,145)"><span>"</span>FooUser<span>"</span></span>,
dependencies: [
<span style="color:rgb(167,29,93)">.</span>Package(
url: <span style="color:rgb(24,54,145)"><span>"</span>../FooLibrary<span>"</span></span>,
majorVersion: <span style="color:rgb(0,134,179)">1</span>,
targets: [<span style="color:rgb(24,54,145)"><span>"</span>Bar<span>"</span></span>])
])</pre></div><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">Note: In this case since Bar depends on Foo, Foo will be also be implicitly built and be available.</p><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">Any target mentioned in <code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px">targets</code> and not present in the package should result in build failure.</p><h2 style="margin-top:1em;margin-bottom:16px;line-height:1.225;font-size:1.75em;padding-bottom:0.3em;border-bottom-width:1px;border-bottom-style:solid;border-bottom-color:rgb(238,238,238);color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol'"><a href="https://github.com/aciidb0mb3r/swift-evolution/tree/swiftpm-module-access-control#impact-on-existing-code" style="background-color:transparent;color:rgb(64,120,192);text-decoration:none;display:inline-block;padding-right:2px;line-height:1" target="_blank"></a>Impact on Existing Code</h2><p style="margin-top:0px;margin-bottom:16px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">There will be no impact on existing code as these features are additive.</p><h2 style="margin-top:1em;margin-bottom:16px;line-height:1.225;font-size:1.75em;padding-bottom:0.3em;border-bottom-width:1px;border-bottom-style:solid;border-bottom-color:rgb(238,238,238);color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol'"><a href="https://github.com/aciidb0mb3r/swift-evolution/tree/swiftpm-module-access-control#alternatives-considered" style="background-color:transparent;color:rgb(64,120,192);text-decoration:none;display:inline-block;padding-right:2px;line-height:1" target="_blank"></a>Alternatives Considered</h2><p style="margin-top:0px;color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px;margin-bottom:0px!important">None at this time.</p></div><span class="HOEnZb"><font color="#888888"><div><br></div>-- <br><div data-smartmail="gmail_signature">Ankit<br><br></div>
<br><br>
</font></span></div>
<br>_______________________________________________<br>
swift-build-dev mailing list<br>
<a href="mailto:swift-build-dev@swift.org">swift-build-dev@swift.org</a><br>
<a href="https://lists.swift.org/mailman/listinfo/swift-build-dev" rel="noreferrer" target="_blank">https://lists.swift.org/mailman/listinfo/swift-build-dev</a><br>
<br></blockquote></div><br></div>