[swift-users] Swift Package Manager and main.swift

[Jordan Rose]

[+swift-dev, bcc swift-users] I’d be fine with supporting “Main.swift”. The one downside is that it could change behavior for existing projects relying on “Main.swift” being a library file, and that might mean it’s not worth making a change.

Jordan


> On May 1, 2016, at 23:34, Kostiantyn Koval via swift-users <swift-users at swift.org> wrote:
> 
> Hi there,
> 
> main is common used naming for executables that contains main function. It’s required by Swift compiler and Swift Package Manager can’t do anything about that.
> If you create a simple command line tool in Xcode, it will create main.swift file. If you try to rename it, it will feil.
> I think this is correct behaviour.
> If you still think that Swift should support Main.swift with upper case letter, than it should be discussed with compiler team.
> 
> - Kostiantyn
> 
> > Hi there,
> > 
> > This is what happened as I was trying out the Swift Package Manager for another project similar to the one shown below:
> > 
> > ~ $ mkdir example
> > ~ $ cd example/
> > example $ touch Package.swift
> > example $ mkdir Sources
> > 
> > example $ vi Sources/Example.swift
> > example $ cat Sources/Example.swift
> > func printOther() {
> > print("other")
> > }
> > 
> > example $ vi Sources/Main.swift
> > example $ cat Sources/Main.swift
> > print("Hello World")
> > printOther()
> > 
> > 
> > example $ swift build
> > Compile Swift Module 'example' (2 sources)
> > /PATH/example/Sources/Main.swift:1:1: error: expressions are not allowed at the top level
> > print("Hello World")
> > ^
> > /PATH/example/Sources/Main.swift:2:1: error: expressions are not allowed at the top level
> > printOther()
> > ^
> > /PATH/example/Sources/Main.swift:1:1: error: expressions are not allowed at the top level
> > print("Hello World")
> > ^
> > /PATH/example/Sources/Main.swift:2:1: error: expressions are not allowed at the top level
> > printOther()
> > ^
> > <unknown>:0: error: build had 1 command failures
> > error: exit(1): /PATH-SWIFT/usr/bin/swift-build-tool -f /PATH/example/.build/debug.yaml
> > 
> > 
> > example $ mv Sources/Main.swift Sources/main.swift
> > example $ swift build
> > Compile Swift Module 'example' (2 sources)
> > Linking .build/debug/example
> > example $ .build/debug/example
> > Hello World
> > other
> > example $
> > 
> > 
> > I had to renameMain.swifttomain.swift. Is there a design decision on why the filename for the main swift file has to be lowercase or is this a bug?
> > 
> > If it’s a design decision, why are directory names forsource files allowed to have variations likeSources,Source,srcandsrcsas statedhere(https://github.com/apple/swift-package-manager/blob/master/Documentation/SourceLayouts.md#other-rules <https://github.com/apple/swift-package-manager/blob/master/Documentation/SourceLayouts.md#other-rules>)but not the main swift file?
> > 
> > I’d be ok if onlyMain.swiftandmain.swiftare allowed since other files in theSourcesdirectory are commonly UpperCamelCasedue to the Type naming conventions e.g.example-package-playingcard/Sources(https://github.com/apple/example-package-playingcard/tree/master/Sources <https://github.com/apple/example-package-playingcard/tree/master/Sources>).
> > 
> > Or maybe I’m just being pedantic?
> > 
> > p.s. evenPackage.swiftis capitalized and notpackage.swift
> > 
> > $ swift --version
> > Swift version 3.0-dev (LLVM 752e1430fc, Clang 1e6cba3ce3, Swift 56052cfe61)
> > Target: x86_64-unknown-linux-gnu
> > 
> > 
> > 
> > 
> > 
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