mirror of
https://github.com/apple/swift-argument-parser.git
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Bassam (Sam) Khouri
a78d98b92d
In some use cases, there is a need to have an option argument behave
like a flag.
This change introduced 4 new intialiazers to `Option` that accept a
`defaultAsFlag` value.
With the following usage:
```swift
struct Example: ParsableCommand {
@Option(defaultAsFlag: "default", help: "Set output format.")
var format: String?
func run() {
print("Format: \(format ?? "none")")
}
}
```
The `defaultAsFlag` parameter creates a hybrid that supports both patterns:
- **Flag behavior**: `--format` (sets format to "default")
- **Option behavior**: `--format json` (sets format to "json")
- **No usage**: format remains `nil`
As a user of the command line tool, the `--help` output clearly distinguishes
between the the hybrid and regular usages.
```
OPTIONS:
--format [<format>] Set output format. (default as flag: default)
````
Note the `(default as flag: ...)` text instead of regular `(default: ...)`,
and the optional value syntax `[<value>]` instead of required `<value>`.
Fixes: #829
55 lines
1.7 KiB
Swift
55 lines
1.7 KiB
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) 2025 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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@main
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struct DefaultAsFlag: ParsableCommand {
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static let configuration = CommandConfiguration(
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abstract: "A utility demonstrating defaultAsFlag options.",
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discussion: """
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This command shows how defaultAsFlag options can work both as flags
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and as options with values.
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"""
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)
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@Option(defaultAsFlag: "default", help: "A string option with defaultAsFlag.")
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var stringFlag: String?
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@Option(defaultAsFlag: 42, help: "An integer option with defaultAsFlag.")
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var numberFlag: Int?
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@Option(defaultAsFlag: true, help: "A boolean option with defaultAsFlag.")
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var boolFlag: Bool?
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@Option(
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defaultAsFlag: "transformed",
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help: "A string option with transform and defaultAsFlag.",
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transform: { $0.uppercased() }
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)
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var transformFlag: String?
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@Option(name: .shortAndLong, help: "A regular option for comparison.")
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var regular: String?
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@Argument
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var additionalArgs: [String] = []
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func run() {
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print("String flag: \(stringFlag?.description ?? "nil")")
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print("Number flag: \(numberFlag?.description ?? "nil")")
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print("Bool flag: \(boolFlag?.description ?? "nil")")
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print("Transform flag: \(transformFlag?.description ?? "nil")")
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print("Regular option: \(regular?.description ?? "nil")")
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print("Additional args: \(additionalArgs)")
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}
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}
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