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https://github.com/apple/swift-argument-parser

Straightforward, type-safe argument parsing for Swift
https://github.com/apple/swift-argument-parser

cli command-line flag option

Last synced: 2 days ago
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Straightforward, type-safe argument parsing for Swift

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README 

        
# Swift Argument Parser



## Usage



Begin by declaring a type that defines the information

that you need to collect from the command line.

Decorate each stored property with one of `ArgumentParser`'s property wrappers,

and then declare conformance to `ParsableCommand` and add the `@main` attribute.

(Note, for `async` renditions of `run`, conform to `AsyncParsableCommand` rather

than `ParsableCommand`.) 

Finally, implement your command's logic in the `run()` method.



```swift

import ArgumentParser



@main

struct Repeat: ParsableCommand {

    @Flag(help: "Include a counter with each repetition.")

    var includeCounter = false



    @Option(name: .shortAndLong, help: "The number of times to repeat 'phrase'.")

    var count: Int? = nil



    @Argument(help: "The phrase to repeat.")

    var phrase: String



    mutating func run() throws {

        let repeatCount = count ?? 2



        for i in 1...repeatCount {

            if includeCounter {

                print("\(i): \(phrase)")

            } else {

                print(phrase)

            }

        }

    }

}

```



The `ArgumentParser` library parses the command-line arguments,

instantiates your command type, and then either executes your `run()` method

or exits with a useful message.



`ArgumentParser` uses your properties' names and type information,

along with the details you provide using property wrappers,

to supply useful error messages and detailed help:



```

$ repeat hello --count 3

hello

hello

hello

$ repeat --count 3

Error: Missing expected argument 'phrase'.

Help:    The phrase to repeat.

Usage: repeat [--count ] [--include-counter] 

  See 'repeat --help' for more information.

$ repeat --help

USAGE: repeat [--count ] [--include-counter] 



ARGUMENTS:

                  The phrase to repeat.



OPTIONS:

  --include-counter       Include a counter with each repetition.

  -c, --count      The number of times to repeat 'phrase'.

  -h, --help              Show help for this command.

```



## Documentation



For guides, articles, and API documentation see the 

[library's documentation on the Web][docs] or in Xcode.



- [ArgumentParser documentation][docs]

- [Getting Started with ArgumentParser](https://swiftpackageindex.com/apple/swift-argument-parser/documentation/argumentparser/gettingstarted)

- [`ParsableCommand` documentation](https://swiftpackageindex.com/apple/swift-argument-parser/documentation/argumentparser/parsablecommand)

- [`AsyncParsableCommand` documentation](https://swiftpackageindex.com/apple/swift-argument-parser/documentation/argumentparser/asyncparsablecommand)



[docs]: https://swiftpackageindex.com/apple/swift-argument-parser/documentation/argumentparser



#### Examples



This repository includes a few examples of using the library:



- [`repeat`](Examples/repeat/Repeat.swift) is the example shown above.

- [`roll`](Examples/roll/main.swift) is a simple utility implemented as a straight-line script.

- [`math`](Examples/math/Math.swift) is an annotated example of using nested commands and subcommands.

- [`count-lines`](Examples/count-lines/CountLines.swift) uses `async`/`await` code in its implementation.



You can also see examples of `ArgumentParser` adoption among Swift project tools:



- [`swift-format`](https://github.com/apple/swift-format/) uses some advanced features, like custom option values and hidden flags.

- [`swift-package-manager`](https://github.com/apple/swift-package-manager/) includes a deep command hierarchy and extensive use of option groups.



## Project Status



The Swift Argument Parser package is source-stable;

version numbers follow semantic versioning.

Source-breaking changes to public API can only land in a new major version.



The public API of version 1.0.0 of the `swift-argument-parser` package

consists of non-underscored declarations that are marked public in the `ArgumentParser` module.

Interfaces that aren't part of the public API may continue to change in any release,

including the exact wording and formatting of the autogenerated help and error messages,

as well as the package’s examples, tests, utilities, and documentation. 



Future minor versions of the package may introduce changes to these rules as needed.



We want this package to quickly embrace Swift language and toolchain improvements that are relevant to its mandate.

Accordingly, from time to time,

we expect that new versions of this package will require clients to upgrade to a more recent Swift toolchain release.

Requiring a new Swift release will only require a minor version bump.



## Adding `ArgumentParser` as a Dependency



To use the `ArgumentParser` library in a SwiftPM project, 

add it to the dependencies for your package and your command-line executable target:



```swift

let package = Package(

    // name, platforms, products, etc.

    dependencies: [

        // other dependencies

        .package(url: "https://github.com/apple/swift-argument-parser", from: "1.3.0"),

    ],

    targets: [

        .executableTarget(name: "", dependencies: [

            // other dependencies

            .product(name: "ArgumentParser", package: "swift-argument-parser"),

        ]),

        // other targets

    ]

)

```



### Supported Versions



The minimum Swift version supported by swift-argument-parser releases are detailed below:



swift-argument-parser | Minimum Swift Version

----------------------|----------------------

`0.0.1 ..< 0.2.0`     | 5.1

`0.2.0 ..< 1.1.0`     | 5.2

`1.1.0 ..< 1.3.0`     | 5.5

`1.3.0 ...`           | 5.7