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

[Kostiantyn Koval]

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)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).
> 
> 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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