- Proposal: SE-0179
- Author: David Hart
- Review Manager: Daniel Dunbar
- Status: Implemented (Swift 4)
- Decision Notes: Rationale
- Implementation: apple/swift-package-manager#1187
The proposal introduces a new
swift run command to build and run an executable defined in the current package.
It is common to want to build and run an executable during development. For now, one must first build it and then execute it from the build folder:
$ swift build $ .build/debug/myexecutable
In Swift 4, the Swift Package Manager will build to a different path, containing a platform sub-folder (
.build/macosx-x86_64/debug for mac and
.build/linux-x86_64/debug for linux), making it more cumbersome to run the executable from the command line.
To improve the development workflow, the proposal suggests introducing a new first-level
swift run command that will build if necessary and then run an executable defined in the
Package.swift manifest, reducing the above steps to just one.
run command would be defined as:
$ swift run --help OVERVIEW: Build and run executable USAGE: swift run [options] [executable [arguments]] OPTIONS: --build-path Specify build/cache directory [default: ./.build] --chdir, -C Change working directory before any other operation --color Specify color mode (auto|always|never) [default: auto] --configuration, -c Build with configuration (debug|release) [default: debug] --enable-prefetching Enable prefetching in resolver --skip-build Skip building the executable product --verbose, -v Increase verbosity of informational output -Xcc Pass flag through to all C compiler invocations -Xlinker Pass flag through to all linker invocations -Xswiftc Pass flag through to all Swift compiler invocations --help Display available options
If needed, the command will build the product before running it. As a result, it can be passed any options
swift build accepts. As for
swift test, it also accepts an extra
--skip-build option to skip the build phase.
After the options, the command optionally takes the name of an executable product defined in the
Package.swift manifest and introduced in SE-0146. If called without an executable and the manifest defines one and only one executable product, it will default to running that one. In any other case, the command fails.
If the executable is explicitly defined, all remaining arguments are passed as-is to the executable.
$ swift run # .build/debug/exe $ swift run exe # .build/debug/exe $ swift run exe arg1 arg2 # .build/debug/exe arg1 arg2
One alternative to the Swift 4 change of build folder would be for the Swift Package Manager to create and update a symlink at
.build/release that point to the latest build folder for that configuration. Although that should probably be done to retain backward-compatibility with tools that depended on the build location, it does not completely invalidate the usefulness of the