Dynamic Members

.travis.yml

@@ -89,11 +89,18 @@ jobs:
 
     - name: CocoaPods
       before_install: |
+        DESCRIPTION=$(swift - <<EOF
+          import Foundation
+          struct Response: Decodable { let description: String }
+          let url = URL(string: "https://api.github.com/repos/mxcl/Path.swift")!
+          let data = try Data(contentsOf: url)
+          print(try JSONDecoder().decode(Response.self, from: data).description)
+        EOF)
         cat <<\ \ EOF> Path.swift.podspec
         Pod::Spec.new do |s|
           s.name = 'Path.swift'
           s.version = 'TRAVIS_TAG'
-          s.summary = 'Delightful, robust file-pathing functions'
+          s.summary = 'DESCRIPTION'
           s.homepage = 'https://github.com/mxcl/Path.swift'
           s.license = { :type => 'Unlicense', :file => 'LICENSE.md' }
           s.author = { 'mxcl' => 'mxcl@me.com' }
@@ -108,6 +115,7 @@ jobs:
         end
         EOF
         sed -i '' "s/TRAVIS_TAG/$TRAVIS_TAG/" Path.swift.podspec
+        sed -i '' "s/DESCRIPTION/$DESCRIPTION/" Path.swift.podspec
       # ^^ see the Jazzy deployment for explanation
       install: gem install cocoapods --pre
       script: pod trunk push

README.md

@@ -94,6 +94,18 @@ decoder.userInfo[.relativePath] = Path.home
 decoder.decode(from: data)
 ```
 
+## Dynamic members
+
+We support `@dynamicMemberLookup`:
+
+```swift
+let ls = Path.root.usr.bin.ls  // => /usr/bin/ls
+```
+
+This is less commonly useful than you would think, hence our documentation
+does not use it. Usually you are joining variables or other `String` arguments.
+However when you need it, it’s *lovely*.
+
 ## Initializing from user-input
 
 The `Path` initializer returns `nil` unless fed an absolute path; thus to

Sources/Path.swift

@@ -23,6 +23,8 @@ import Foundation
  - Note: There may not be an actual filesystem entry at the path. The underlying
    representation for `Path` is `String`.
  */
+
+@dynamicMemberLookup
 public struct Path: Equatable, Hashable, Comparable {
 
     init(string: String) {
@@ -45,6 +47,12 @@ public struct Path: Equatable, Hashable, Comparable {
         return URL(fileURLWithPath: string)
     }
 
+    /// Facilitates constructing paths for static strings
+    public subscript(dynamicMember pathComponent: String) -> Path {
+        let str = (string as NSString).appendingPathComponent(pathComponent)
+        return Path(string: str)
+    }
+
     /**
      Returns the parent directory for this path.
 

Tests/PathTests/PathTests.swift

@@ -14,10 +14,10 @@ class PathTests: XCTestCase {
     func testEnumeration() throws {
         let tmpdir_ = try TemporaryDirectory()
         let tmpdir = tmpdir_.path
-        try tmpdir.join("a").mkdir().join("c").touch()
-        try tmpdir.join("b").touch()
-        try tmpdir.join("c").touch()
-        try tmpdir.join(".d").mkdir().join("e").touch()
+        try tmpdir.a.mkdir().c.touch()
+        try tmpdir.b.touch()
+        try tmpdir.c.touch()
+        try tmpdir.join(".d").mkdir().e.touch()
 
         var paths = Set<String>()
         var dirs = 0
@@ -139,6 +139,13 @@ class PathTests: XCTestCase {
         XCTAssertEqual(Path.root/"a/foo"/"../../../bar", Path.root/"bar")
     }
 
+    func testDynamicMember() {
+        XCTAssertEqual(Path.root.Documents, Path.root/"Documents")
+
+        let a = Path.home.foo
+        XCTAssertEqual(a.Documents, Path.home/"foo/Documents")
+    }
+
     func testCopyInto() throws {
         try Path.mktemp { root in
             let bar = try root.join("bar").touch()

Tests/PathTests/XCTestManifests.swift

@@ -6,6 +6,7 @@ extension PathTests {
         ("testCodable", testCodable),
         ("testConcatenation", testConcatenation),
         ("testCopyInto", testCopyInto),
+        ("testDynamicMember", testDynamicMember),
         ("testEnumeration", testEnumeration),
         ("testEnumerationSkippingHiddenFiles", testEnumerationSkippingHiddenFiles),
         ("testExists", testExists),