Adds Optional.publisher as a convenience for Optional.Publisher.init. (#32)

Author: jasdev

CombineExt.xcodeproj/project.pbxproj

@@ -60,6 +60,8 @@
 		BF9D85D724450090001783E6 /* ShareReplayTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF9D85D624450090001783E6 /* ShareReplayTests.swift */; };
 		BFB4EA132428256B0096E9E9 /* CombineLatestMany.swift in Sources */ = {isa = PBXBuildFile; fileRef = BFB4EA122428256B0096E9E9 /* CombineLatestMany.swift */; };
 		BFB4EA1524283ECF0096E9E9 /* CombineLatestManyTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = BFB4EA1424283ECF0096E9E9 /* CombineLatestManyTests.swift */; };
+		BFF0BFF12469D7D800399570 /* Optional.swift in Sources */ = {isa = PBXBuildFile; fileRef = BFF0BFF02469D7D800399570 /* Optional.swift */; };
+		BFF0BFF52469D92C00399570 /* OptionalTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = BFF0BFF42469D92C00399570 /* OptionalTests.swift */; };
 		DC16910F24281A1800B234C4 /* MapMany.swift in Sources */ = {isa = PBXBuildFile; fileRef = DC16910E24281A1800B234C4 /* MapMany.swift */; };
 		DC1691122428228200B234C4 /* MapManyTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = DC1691112428228200B234C4 /* MapManyTests.swift */; };
 		OBJ_22 /* AssignToMany.swift in Sources */ = {isa = PBXBuildFile; fileRef = OBJ_9 /* AssignToMany.swift */; };
@@ -117,6 +119,8 @@
 		BF9D85D624450090001783E6 /* ShareReplayTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ShareReplayTests.swift; sourceTree = "<group>"; };
 		BFB4EA122428256B0096E9E9 /* CombineLatestMany.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CombineLatestMany.swift; sourceTree = "<group>"; };
 		BFB4EA1424283ECF0096E9E9 /* CombineLatestManyTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CombineLatestManyTests.swift; sourceTree = "<group>"; };
+		BFF0BFF02469D7D800399570 /* Optional.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Optional.swift; sourceTree = "<group>"; };
+		BFF0BFF42469D92C00399570 /* OptionalTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = OptionalTests.swift; sourceTree = "<group>"; };
 		"CombineExt::CombineExt::Product" /* CombineExt.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; path = CombineExt.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		"CombineExt::CombineExtTests::Product" /* CombineExtTests.xctest */ = {isa = PBXFileReference; lastKnownFileType = file; path = CombineExtTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		DC16910E24281A1800B234C4 /* MapMany.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MapMany.swift; sourceTree = "<group>"; };
@@ -190,6 +194,14 @@
 			path = Subjects;
 			sourceTree = "<group>";
 		};
+		BFF0BFEF2469D7A500399570 /* Convenience */ = {
+			isa = PBXGroup;
+			children = (
+				BFF0BFF02469D7D800399570 /* Optional.swift */,
+			);
+			path = Convenience;
+			sourceTree = "<group>";
+		};
 		OBJ_11 /* Tests */ = {
 			isa = PBXGroup;
 			children = (
@@ -212,6 +224,7 @@
 				BF9D85D42444D12F001783E6 /* ReplaySubjectTests.swift */,
 				BF9D85D624450090001783E6 /* ShareReplayTests.swift */,
 				BF8EDF4D2453540D00B0CC75 /* PrefixDurationTests.swift */,
+				BFF0BFF42469D92C00399570 /* OptionalTests.swift */,
 			);
 			path = Tests;
 			sourceTree = SOURCE_ROOT;
@@ -240,6 +253,7 @@
 		OBJ_7 /* Sources */ = {
 			isa = PBXGroup;
 			children = (
+				BFF0BFEF2469D7A500399570 /* Convenience */,
 				BF9D85D12444BB7F001783E6 /* Subjects */,
 				78C193DA241D07160001B7FD /* Common */,
 				78C193D5241C2E4F0001B7FD /* Models */,
@@ -378,6 +392,7 @@
 			files = (
 				BF3C6B6C24421D27004D4A8A /* ShareReplay.swift in Sources */,
 				DC16910F24281A1800B234C4 /* MapMany.swift in Sources */,
+				BFF0BFF12469D7D800399570 /* Optional.swift in Sources */,
 				78C193CF241C16C40001B7FD /* FlatMapLatest.swift in Sources */,
 				78C193DC241D0A9F0001B7FD /* Sink.swift in Sources */,
 				788CD8FB2431228C0015B3C7 /* Amb.swift in Sources */,
@@ -416,6 +431,7 @@
 			buildActionMask = 0;
 			files = (
 				78C193D2241C1B750001B7FD /* FlatMapLatestTests.swift in Sources */,
+				BFF0BFF52469D92C00399570 /* OptionalTests.swift in Sources */,
 				78AA9297241B8532009BD68B /* AssignToManyTests.swift in Sources */,
 				BFB4EA1524283ECF0096E9E9 /* CombineLatestManyTests.swift in Sources */,
 				71E6F4EE2465616100FB4103 /* AssignOwnershipTests.swift in Sources */,

README.md

@@ -45,6 +45,9 @@ All operators, utilities and helpers respect Combine's publisher contract, inclu
 ### Subjects
 * [ReplaySubject](#ReplaySubject)
 
+### Convenience
+* [Optional.publisher](#Optionalpublisher)
+
 > **Note**: This is still a relatively early version of CombineExt, with much more to be desired. I gladly accept PRs, ideas, opinions, or improvements. Thank you! :)
 
 ## Installation
@@ -642,6 +645,28 @@ subject.send(5)
 5
 ```
 
+## Convenience
+
+## Optional.publisher
+
+`Optional.publisher` is a property version of [`Optional.Publisher.init`](https://developer.apple.com/documentation/swift/optional/publisher/3343960-init). It puts the type on equal footing with [`Result.publisher`](https://developer.apple.com/documentation/swift/result/3344716-publisher) and [`Sequence.publisher`](https://developer.apple.com/documentation/swift/sequence/3344717-publisher).
+
+So you can use:
+
+```swift
+let number: Int? = 1
+number.publisher
+  /* … */
+```
+
+Instead of:
+
+```swift
+let number: Int? = 1
+Optional.Publisher(number)
+  /* … */
+```
+
 ## License
 
 MIT, of course ;-) See the [LICENSE](LICENSE) file. 

Sources/Convenience/Optional.swift

@@ -0,0 +1,19 @@
+//
+//  Optional.swift
+//  CombineExt
+//
+//  Created by Jasdev Singh on 11/05/2020.
+//  Copyright © 2020 Combine Community. All rights reserved.
+//
+
+#if canImport(Combine)
+import Combine
+
+@available(OSX 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+public extension Optional {
+    /// A publisher that publishes an optional value to each subscriber exactly once, if the optional has a value.
+    var publisher: Optional.Publisher {
+        Optional.Publisher(self)
+    }
+}
+#endif

Tests/OptionalTests.swift

@@ -0,0 +1,44 @@
+//
+//  OptionalTests.swift
+//  CombineExt
+//
+//  Created by Jasdev Singh on 11/05/2020.
+//  Copyright © 2020 Combine Community. All rights reserved.
+//
+
+#if !os(watchOS)
+import Combine
+import CombineExt
+import XCTest
+
+@available(OSX 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+final class OptionalTests: XCTestCase {
+    private var subscription: AnyCancellable!
+
+    func testSomeInitialization() {
+        var results = [Int]()
+        var completion: Subscribers.Completion<Never>?
+
+        subscription = Optional(1)
+            .publisher
+            .sink(receiveCompletion: { completion = $0 },
+                  receiveValue: { results.append($0) })
+
+        XCTAssertEqual([1], results)
+        XCTAssertEqual(.finished, completion)
+    }
+
+    func testNoneInitialization() {
+        var results = [Int]()
+        var completion: Subscribers.Completion<Never>?
+
+        subscription = Optional<Int>.none
+            .publisher
+            .sink(receiveCompletion: { completion = $0 },
+                  receiveValue: { results.append($0) })
+
+        XCTAssertTrue(results.isEmpty)
+        XCTAssertEqual(.finished, completion)
+    }
+}
+#endif

Tests/PrefixDurationTests.swift

@@ -47,7 +47,7 @@ final class PrefixDurationTests: XCTestCase {
         var completions = [Subscribers.Completion<Never>]()
 
         cancellable = subject
-            .prefix(duration: 0.5)
+            .prefix(duration: 0.8)
             .sink(receiveCompletion: { completions.append($0); expectation.fulfill() },
                   receiveValue: { results.append($0) })
 
@@ -61,7 +61,7 @@ final class PrefixDurationTests: XCTestCase {
             subject.send(3)
         }
 
-        DispatchQueue.main.asyncAfter(deadline: .now() + 0.75) {
+        DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
             subject.send(4)
             subject.send(5)
             subject.send(completion: .finished)