[SR-11432] Declarative package description for SwiftPM using Function Builders

[swift-ci]

Previous ID	SR-11432
Radar	None
Original Reporter	kitasuke (JIRA User)
Type	New Feature
Status	Closed
Resolution	Won't Do

Additional Detail from JIRA

Votes	0
Component/s	Package Manager
Labels	New Feature
Assignee	kitasuke (JIRA)
Priority	Medium

md5: 063f185e77f07f6591ed8271b385975c

Issue Description:

Overview

I would like to make a propose to have declarative package description by using function builder as alternative way. I think we can keep current way as it is.

There are pros and cons. This case might not work with function builders because package description has type constraints in the tree structure, but I would love to hear your opinions.

Pros

• Declarative description

• More understandable API

Cons

• Can't have type constraints for all of contents unless we defined function builder for specific types

• Compiler error is not friendly when we have wrong content at unexpected place

let package = Package(name: "Paper") {
    ProductList {
        Product(name: "tool", type: .static) {
            TargetList {
                Target(name: "tool")
            }
        }
    }
    DependencyList {
        Dependency(
            url: "http://example.com.com/ExamplePackage/ExamplePackage",
            from: "1.2.3"
        )
        Dependency(url: "dev", exact: "1.2.3")
    }
    TargetList {
        Target(name: "tool") {
            TargetDependencyList {
                TargetDependency(name: "Paper")
                TargetDependency(name: "ExamplePackage")
            }
        }
        Target(name: "Paper") {
            TargetDependencyList {
                TargetDependency(name: "Basic")
                Target(name: "Utility")
                Product(name: "AnotherExamplePackage")
            }
        }
    }
}

Here is my rough implementation of the functionality. Encoded data would be interface for current implementation of package description.

https://gist.github.com/kitasuke/ee73934c2eda0f63bbd371b69380c443

With this implementation, description above can be encoded because it conforms to Encodable, so that this can be mapped to existing structure easily. Here is sample encoded output as JSON

{
  "targets": [
    {
      "name": "tool",
      "dependencies": [
        {
          "name": "Paper"
        },
        {
          "name": "ExamplePackage"
        }
      ]
    },
    {
      "name": "Paper",
      "dependencies": [
        {
          "name": "Basic"
        },
        {
          "name": "Utility"
        },
        {
          "name": "AnotherExamplePackage",
          "type": "executable"
        }
      ]
    }
  ],
  "name": "Paper",
  "dependencies": [
    {
      "url": "http://example.com.com/ExamplePackage/ExamplePackage",
      "from": "1.2.3"
    },
    {
      "url": "dev",
      "exact": "1.2.3"
    }
  ],
  "products": [
    {
      "name": "tool",
      "type": "static",
      "targets": [
        {
          "name": "tool"
        }
      ]
    }
  ]
}

[aciidgh]

kitasuke (JIRA User) Thanks for working on this! We should discuss this on the forums so a wider audience can pitch in. Can you post this in the SwiftPM development category: https://forums.swift.org/c/development/SwiftPM

[swift-ci]

Comment by Yusuke Kita (JIRA)

Posted: https://forums.swift.org/t/declarative-package-description-for-swiftpm-using-function-builders/28699