mirror of
https://github.com/apple/swift-argument-parser.git
synced 2026-06-06 20:18:23 +00:00
Nate Cook
0bac2cc0f1
This adds underscored initializers that let library users add `= nil` to declarations of optional `@Option` and `@Argument` properties. Previously, default values have been available for properties of non-optional types only. These new initializers use `_OptionalNilComparisonType` as the wrapped value parameter, so only a `nil` literal is acceptable in the default value position. This avoids the problem of declaring an optional property with a non-`nil` default, which ends up negating the purpose of an optional.
49 lines
1.5 KiB
Swift
49 lines
1.5 KiB
Swift
//===----------------------------------------------------------*- swift -*-===//
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//
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// This source file is part of the Swift Argument Parser open source project
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//
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// Copyright (c) 2020 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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//
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//===----------------------------------------------------------------------===//
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import ArgumentParser
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struct RollOptions: ParsableArguments {
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@Option(help: ArgumentHelp("Rolls the dice <n> times.", valueName: "n"))
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var times = 1
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@Option(help: ArgumentHelp(
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"Rolls an <m>-sided dice.",
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discussion: "Use this option to override the default value of a six-sided die.",
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valueName: "m"))
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var sides = 6
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@Option(help: "A seed to use for repeatable random generation.")
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var seed: Int? = nil
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@Flag(name: .shortAndLong, help: "Show all roll results.")
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var verbose = false
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}
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// If you prefer writing in a "script" style, you can call `parseOrExit()` to
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// parse a single `ParsableArguments` type from command-line arguments.
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let options = RollOptions.parseOrExit()
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let seed = options.seed ?? .random(in: .min ... .max)
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var rng = SplitMix64(seed: UInt64(truncatingIfNeeded: seed))
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let rolls = (1...options.times).map { _ in
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Int.random(in: 1...options.sides, using: &rng)
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}
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if options.verbose {
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for (number, roll) in zip(1..., rolls) {
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print("Roll \(number): \(roll)")
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}
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}
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print(rolls.reduce(0, +))
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