SourceryPlayground

Type safety for generating Sourcery Swift templates.

Sourcery is a widely-popular code generation library for Swift development. Given a template and Swift input file(s), Sourcery can generate additional code for your project. This repository is meant to assist developers in writing their own Sourcery templates.

Background

Developers can write templates in Swift via files with the .swifttemplate extension. There exists some brief Sourcery documentation on the format, but in essence, the templates are just Swift files leveraging the SourceryRuntime source files located here with some syntax to distinguish codegen output versus control flow. However, as you’re writing .swifttemplate files instead of actual .swift files, developers usually can't take advantage of type safety or autocomplete as they’re writing these templates. That is where this playground can help.

Usage

TL;DR run the Playground and play with the contained source code.

// For an enum with (intValue: Int) as an associated type,
// and a suffix of "LHS", returns "(let intValueLHS)"
func associatedValueList(enumCase: EnumCase, suffix: String) -> String {
    let list = enumCase.associatedValues
        .map({ value in
            guard let name = value.localName else {
                fatalError("AutoEquatable enums should have associated types with labels")
            }
            return "let \(name)\(suffix)"
        })
        .joined(separator: ", ")
    return enumCase.associatedValues.isEmpty ? "" : "(\(list))"
}

Write your .swifttemplate helper functions in Playground.playground, which has the SourceryRuntime files dropped in. Then, when you're ready to test the output, drop the code into your project.

You can't yet provide test cases right in the Playground, because there isn't a convenient way to stub the Sourcery models, such as EnumCase above.

Updating Sourcery

The Automated Part

The update_sourcery.sh script clones the Sourcery repository and copies the files in the SourceryRuntime directory into the Playground's sources.

The Manual Part

Xcode Playgrounds can get a no such module error if any files in its Sources imports a custom module. As so, after running update_sourcery.sh , it may be necessary to manually edit the SourceryRuntime source files to get the Playground running. It's also possible that the contents of SourceryRuntime change in such a way where it's unviable to make the necessary manual edits, and this playground becomes unsupported. We’re here for a good time, not a long time.

Current Version

The source files in this playground are from Sourcery 0.13.1 See the diffs from any manual source file edits here.