Registering / Enabling shortcuts now returns a discardable Bool to know if registering worked or not

Also adds an "isEnabled" calculated property to Shortcut, and the appropriate .shortcutIsEnabled(_ : ) function to KeyboardShortcuts.

Makes var isTakenBySystem public so it can be used for "default" shortcuts created by an app.

Sources/KeyboardShortcuts/CarbonKeyboardShortcuts.swift

@@ -37,34 +37,32 @@ enum CarbonKeyboardShortcuts {
 	private static var hotKeyId = 0
 	private static var eventHandler: EventHandlerRef?
 
-	private static func setUpEventHandlerIfNeeded() {
-		guard
-			eventHandler == nil,
-			let dispatcher = GetEventDispatcherTarget()
-		else {
-			return
-		}
+	private static func setUpEventHandlerIfNeeded() -> Bool {
+		guard eventHandler == nil else { return true }
+		guard let dispatcher = GetEventDispatcherTarget() else { return false }
 
 		let eventSpecs = [
 			EventTypeSpec(eventClass: OSType(kEventClassKeyboard), eventKind: UInt32(kEventHotKeyPressed)),
 			EventTypeSpec(eventClass: OSType(kEventClassKeyboard), eventKind: UInt32(kEventHotKeyReleased))
 		]
 
-		InstallEventHandler(
+		guard InstallEventHandler(
 			dispatcher,
 			carbonKeyboardShortcutsEventHandler,
 			eventSpecs.count,
 			eventSpecs,
 			nil,
 			&eventHandler
-		)
+		) == noErr else { return false }
+		
+		return true
 	}
 
-	static func register(
+	@discardableResult static func register(
 		_ shortcut: KeyboardShortcuts.Shortcut,
 		onKeyDown: @escaping (KeyboardShortcuts.Shortcut) -> Void,
 		onKeyUp: @escaping (KeyboardShortcuts.Shortcut) -> Void
-	) {
+	) -> Bool {
 		hotKeyId += 1
 
 		var eventHotKey: EventHotKeyRef?
@@ -81,7 +79,7 @@ enum CarbonKeyboardShortcuts {
 			registerError == noErr,
 			let carbonHotKey = eventHotKey
 		else {
-			return
+			return false
 		}
 
 		hotKeys[hotKeyId] = HotKey(
@@ -92,7 +90,7 @@ enum CarbonKeyboardShortcuts {
 			onKeyUp: onKeyUp
 		)
 
-		setUpEventHandlerIfNeeded()
+		return setUpEventHandlerIfNeeded()
 	}
 
 	private static func unregisterHotKey(_ hotKey: HotKey) {

Sources/KeyboardShortcuts/KeyboardShortcuts.swift

@@ -37,18 +37,22 @@ public enum KeyboardShortcuts {
 	*/
 	static var isPaused = false
 
-	private static func register(_ shortcut: Shortcut) {
+	@discardableResult private static func register(_ shortcut: Shortcut) -> Bool {
 		guard !registeredShortcuts.contains(shortcut) else {
-			return
+			return true //already registered
 		}
 
-		CarbonKeyboardShortcuts.register(
+		let keyboardShortcutRegistered = CarbonKeyboardShortcuts.register(
 			shortcut,
 			onKeyDown: handleOnKeyDown,
 			onKeyUp: handleOnKeyUp
 		)
 
+		guard keyboardShortcutRegistered else { return false }
+		
 		registeredShortcuts.insert(shortcut)
+		
+		return true
 	}
 
 	/**
@@ -129,12 +133,19 @@ public enum KeyboardShortcuts {
 	/**
 	Enable a disabled keyboard shortcut.
 	*/
-	public static func enable(_ name: Name) {
+	@discardableResult public static func enable(_ name: Name) -> Bool {
 		guard let shortcut = getShortcut(for: name) else {
-			return
+			return false
 		}
 
-		register(shortcut)
+		return register(shortcut)
+	}
+	
+	/**
+	 Returns whether the passed-in shortcut is currently registered.
+	 */
+	public static func shortcutIsEnabled(_ shortcut: Shortcut) -> Bool {
+		return registeredShortcuts.contains(shortcut) || registeredShortcuts.first(where: {$0.key == shortcut.key && $0.modifiers == shortcut.modifiers}) != nil
 	}
 
 	/**

Sources/KeyboardShortcuts/Shortcut.swift

@@ -38,6 +38,13 @@ extension KeyboardShortcuts {
 		You most likely don't need this.
 		*/
 		public let carbonModifiers: Int
+		
+		/**
+		 Returns whether this shortcut is registered/enabled.
+		 */
+		public var isEnabled: Bool {
+			KeyboardShortcuts.shortcutIsEnabled(self)
+		}
 
 		/**
 		Initialize from a strongly-typed key and modifiers.
@@ -97,7 +104,7 @@ extension KeyboardShortcuts.Shortcut {
 	/**
 	Check whether the keyboard shortcut is already taken by the system.
 	*/
-	var isTakenBySystem: Bool {
+	public var isTakenBySystem: Bool {
 		guard self != Self(.f12, modifiers: []) else {
 			return false
 		}