Allow normal Swift default property initialization syntax

Documentation/02 Arguments, Options, and Flags.md

@@ -27,13 +27,13 @@ The three preceding examples could be calls of this `Example` command:
 ```swift
 struct Example: ParsableCommand {
     @Argument() var files: [String]
-    
+
     @Option() var count: Int?
-    
-    @Option(default: 0) var index: Int
-    
+
+    @Option var index: Int = 0
+
     @Flag() var verbose: Bool
-    
+
     @Flag() var stripWhitespace: Bool
 }
 ```
@@ -51,7 +51,7 @@ Users must provide values for all properties with no implicit or specified defau
 struct Example: ParsableCommand {
     @Option()
     var userName: String
-    
+
     @Argument()
     var value: Int
 }
@@ -105,13 +105,13 @@ You can override this default by specifying one or more name specifications in t
 struct Example: ParsableCommand {
     @Flag(name: .long)  // Same as the default
     var stripWhitespace: Bool
-    
+
     @Flag(name: .short)
     var verbose: Bool
-    
+
     @Option(name: .customLong("count"))
     var iterationCount: Int
-    
+
     @Option(name: [.customShort("I"), .long])
     var inputFile: String
 }
@@ -147,7 +147,7 @@ You can make your own custom types conform to `ExpressibleByArgument` by impleme
 ```swift
 struct Path: ExpressibleByArgument {
     var pathString: String
-    
+
     init?(argument: String) {
         self.pathString = argument
     }
@@ -167,7 +167,7 @@ enum ReleaseMode: String, ExpressibleByArgument {
 
 struct Example: ParsableCommand {
     @Option() var mode: ReleaseMode
-    
+
     mutating func run() throws {
         print(mode)
     }
@@ -189,7 +189,7 @@ To use a non-`ExpressibleByArgument` type for an argument or option, you can ins
 enum Format {
     case text
     case other(String)
-    
+
     init(_ string: String) throws {
         if string == "text" {
             self = .text
@@ -209,23 +209,23 @@ Throw an error from the `transform` function to indicate that the user provided
 
 ## Using flag inversions, enumerations, and counts
 
-Flags are most frequently used for `Bool` properties, with a default value of `false`. You can generate a `true`/`false` pair of flags by specifying a flag inversion:
+Flags are most frequently used for `Bool` properties. You can generate a `true`/`false` pair of flags by specifying a flag inversion:
 
 ```swift
 struct Example: ParsableCommand {
-    @Flag(default: true, inversion: .prefixedNo)
-    var index: Bool
+    @Flag(inversion: .prefixedNo)
+    var index: Bool = true
 
-    @Flag(default: nil, inversion: .prefixedEnableDisable)
+    @Flag(inversion: .prefixedEnableDisable)
     var requiredElement: Bool
-    
+
     mutating func run() throws {
         print(index, requiredElement)
     }
 }
 ```
 
-When providing a flag inversion, you can pass your own default as the `default` parameter. If you want to require that the user specify one of the two inversions, pass `nil` as the `default` parameter.
+When providing a flag inversion, you can pass your own default with normal property initialization syntax (`@Flag var foo: Bool = true`). If you want to require that the user specify one of the two inversions, use a non-Optional type and do not pass a default value.
 
 In the `Example` command defined above, a flag is required for the `requiredElement` property. The specified prefixes are prepended to the long names for the flags:
 
@@ -252,23 +252,23 @@ enum Color: EnumerableFlag {
 
 struct Example: ParsableCommand {
     @Flag() var cacheMethod: CacheMethod
-    
+
     @Flag() var colors: [Color]
-    
+
     mutating func run() throws {
         print(cacheMethod)
         print(colors)
     }
 }
-``` 
+```
 
 The flag names in this case are drawn from the raw values — for information about customizing the names and help text, see the  [`EnumerableFlag` documentation](../Sources/ArgumentParser/Parsable%20Types/EnumerableFlag.swift).
 
 ```
 % example --in-memory-cache --pink --silver
 .inMemoryCache
 [.pink, .silver]
-% example 
+% example
 Error: Missing one of: '--in-memory-cache', '--persistent-cache'
 ```
 
@@ -278,7 +278,7 @@ Finally, when a flag is of type `Int`, the value is parsed as a count of the num
 struct Example: ParsableCommand {
     @Flag(name: .shortAndLong)
     var verbose: Int
-    
+
     mutating func run() throws {
         print("Verbosity level: \(verbose)")
     }
@@ -305,7 +305,7 @@ struct Example: ParsableCommand {
     @Flag() var verbose: Bool
     @Option() var name: String
     @Argument() var file: String?
-    
+
     mutating func run() throws {
         print("Verbose: \(verbose), name: \(name), file: \(file ?? "none")")
     }
@@ -351,7 +351,7 @@ The default strategy for parsing options as arrays is to read each value from a
 struct Example: ParsableCommand {
     @Option() var file: [String]
     @Flag() var verbose: Bool
-    
+
     mutating func run() throws {
         print("Verbose: \(verbose), files: \(file)")
     }
@@ -402,7 +402,7 @@ The default strategy for parsing arrays of positional arguments is to ignore  al
 struct Example: ParsableCommand {
     @Flag() var verbose: Bool
     @Argument() var files: [String]
-    
+
     mutating func run() throws {
         print("Verbose: \(verbose), files: \(files)")
     }

Documentation/03 Commands and Subcommands.md

@@ -68,25 +68,25 @@ It's time to define our first two subcommands: `Add` and `Multiply`. Both of the
 ```swift
 extension Math {
     struct Add: ParsableCommand {
-        static var configuration 
+        static var configuration
             = CommandConfiguration(abstract: "Print the sum of the values.")
 
         @OptionGroup()
         var options: Math.Options
-        
+
         mutating func run() {
             let result = options.values.reduce(0, +)
             print(format(result: result, usingHex: options.hexadecimalOutput))
         }
     }
 
     struct Multiply: ParsableCommand {
-        static var configuration 
+        static var configuration
             = CommandConfiguration(abstract: "Print the product of the values.")
 
         @OptionGroup()
         var options: Math.Options
-        
+
         mutating func run() {
             let result = options.values.reduce(1, *)
             print(format(result: result, usingHex: options.hexadecimalOutput))
@@ -98,7 +98,7 @@ extension Math {
 Next, we'll define `Statistics`, the third subcommand of `Math`. The `Statistics` command specifies a custom command name (`stats`) in its configuration, overriding the default derived from the type name (`statistics`). It also declares two additional subcommands, meaning that it acts as a forked branch in the command tree, and not a leaf.
 
 ```swift
-extension Math {   
+extension Math {
     struct Statistics: ParsableCommand {
         static var configuration = CommandConfiguration(
             commandName: "stats",
@@ -115,21 +115,21 @@ extension Math.Statistics {
     struct Average: ParsableCommand {
         static var configuration = CommandConfiguration(
             abstract: "Print the average of the values.")
-        
+
         enum Kind: String, ExpressibleByArgument {
             case mean, median, mode
         }
 
-        @Option(default: .mean, help: "The kind of average to provide.")
-        var kind: Kind
-        
+        @Option(help: "The kind of average to provide.")
+        var kind: Kind = .mean
+
         @Argument(help: "A group of floating-point values to operate on.")
         var values: [Double]
-                
+
         func calculateMean() -> Double { ... }
         func calculateMedian() -> Double { ... }
         func calculateMode() -> [Double] { ... }
-    
+
         mutating func run() {
             switch kind {
             case .mean:
@@ -144,15 +144,15 @@ extension Math.Statistics {
             }
         }
     }
-    
+
     struct StandardDeviation: ParsableCommand {
         static var configuration = CommandConfiguration(
             commandName: "stdev",
             abstract: "Print the standard deviation of the values.")
-        
+
         @Argument(help: "A group of floating-point values to operate on.")
         var values: [Double]
-        
+
         mutating func run() {
             if values.isEmpty {
                 print(0.0)

Documentation/04 Customizing Help.md

@@ -2,16 +2,16 @@
 
 Support your users (and yourself) by providing rich help for arguments and commands.
 
-You can provide help text when declaring any `@Argument`, `@Option`, or `@Flag` by passing a string literal as the `help` parameter: 
+You can provide help text when declaring any `@Argument`, `@Option`, or `@Flag` by passing a string literal as the `help` parameter:
 
 ```swift
 struct Example: ParsableCommand {
     @Flag(help: "Display extra information while processing.")
     var verbose: Bool
-    
-    @Option(default: 0, help: "The number of extra lines to show.")
-    var extraLines: Int
-    
+
+    @Option(help: "The number of extra lines to show.")
+    var extraLines: Int = 0
+
     @Argument(help: "The input file.")
     var inputFile: String?
 }
@@ -24,10 +24,10 @@ Users see these strings in the automatically-generated help screen, which is tri
 USAGE: example [--verbose] [--extra-lines <extra-lines>] <input-file>
 
 ARGUMENTS:
-  <input-file>            The input file. 
+  <input-file>            The input file.
 
 OPTIONS:
-  --verbose               Display extra information while processing. 
+  --verbose               Display extra information while processing.
   --extra-lines <extra-lines>
                           The number of extra lines to show. (default: 0)
   -h, --help              Show help information.
@@ -43,12 +43,12 @@ Here's the same command with some extra customization:
 struct Example: ParsableCommand {
     @Flag(help: "Display extra information while processing.")
     var verbose: Bool
-    
-    @Option(default: 0, help: ArgumentHelp(
+
+    @Option(help: ArgumentHelp(
         "The number of extra lines to show.",
         valueName: "n"))
-    var extraLines: Int
-    
+    var extraLines: Int = 0
+
     @Argument(help: ArgumentHelp(
         "The input file.",
         discussion: "If no input file is provided, the tool reads from stdin.",
@@ -63,11 +63,11 @@ struct Example: ParsableCommand {
 USAGE: example [--verbose] [--extra-lines <n>] [<file>]
 
 ARGUMENTS:
-  <file>                  The input file. 
+  <file>                  The input file.
         If no input file is provided, the tool reads from stdin.
 
 OPTIONS:
-  --verbose               Display extra information while processing. 
+  --verbose               Display extra information while processing.
   --extra-lines <n>       The number of extra lines to show. (default: 0)
   -h, --help              Show help information.
 ```
@@ -83,10 +83,10 @@ struct Repeat: ParsableCommand {
         discussion: """
             Prints to stdout forever, or until you halt the program.
             """)
-            
+
     @Argument(help: "The phrase to repeat.")
     var phrase: String
-    
+
     mutating func run() throws {
         while true { print(phrase) }
     }
@@ -104,7 +104,7 @@ Prints to stdout forever, or until you halt the program.
 USAGE: repeat <phrase>
 
 ARGUMENTS:
-  <phrase>                The phrase to repeat. 
+  <phrase>                The phrase to repeat.
 
 OPTIONS:
   -h, --help              Show help information.
@@ -127,10 +127,10 @@ Users can see the help screen for a command by passing either the `-h` or the `-
 struct Example: ParsableCommand {
     static let configuration = CommandConfiguration(
         helpNames: [.long, .customShort("?")])
-        
+
     @Option(name: .shortAndLong, help: "The number of history entries to show.")
     var historyDepth: Int
-    
+
     mutating func run() throws {
         printHistory(depth: historyDepth)
     }
@@ -146,7 +146,7 @@ When running the command, `-h` matches the short name of the `historyDepth` prop
 USAGE: example --history-depth <history-depth>
 
 ARGUMENTS:
-  <phrase>                The phrase to repeat. 
+  <phrase>                The phrase to repeat.
 
 OPTIONS:
   -h, --history-depth     The number of history entries to show.
@@ -155,7 +155,7 @@ OPTIONS:
 
 ## Hiding Arguments and Commands
 
-You may want to suppress features under development or experimental flags from the generated help screen. You can hide an argument or a subcommand by passing `shouldDisplay: false` to the property wrapper or `CommandConfiguration` initializers, respectively. 
+You may want to suppress features under development or experimental flags from the generated help screen. You can hide an argument or a subcommand by passing `shouldDisplay: false` to the property wrapper or `CommandConfiguration` initializers, respectively.
 
 `ArgumentHelp` includes a `.hidden` static property that makes it even simpler to hide arguments: