Embed Ruby in Swift: load Gems, run Ruby scripts, invoke APIs seamlessly in both directions.
RubyGateway is a framework built on the Ruby C API that lets Swift programs running on macOS or Linux painlessly and safely run and interact with Ruby programs. It's easy to pass Swift values into Ruby and turn Ruby objects back into Swift types.
RubyGateway lets you call any Ruby method from Swift, including passing Swift closures as blocks. It lets you define Ruby classes and methods that are implemented in Swift.
See CRuby if you are looking for a low-level Ruby C API wrapper.
Rouge is a code highlighter. In Ruby:
require 'rouge'
html = Rouge.highlight("let a = 3", "swift", "html")
puts(html)In Swift:
import RubyGateway
try Ruby.require(filename: "rouge")
let html = try Ruby.get("Rouge").call("highlight", args: ["let a = 3", "swift", "html"])
print(html)// Create an object. Use keyword arguments with initializer
let student = RbObject(ofClass: "Academy::Student", kwArgs: ["name": "barney"])!
// Acess an attribute
print("Name is \(student.get("name"))")
// Fix their name by poking an ivar
try! student.setInstanceVar("@name", newValue: "Barney")
// Get a Swift version of `:reading`
let readingSubject = RbSymbol("reading")
// Call a method with mixed Swift data types
try! student.call("add_score", args: [readingSubject, 30])
try! student.call("add_score", args: [readingSubject, 35])
// Get a result as floating point
let avgScoreObj = try! student.call("mean_score_for_subject", args: [readingSubject])
let avgScore = Double(avgScoreObj)!
print("Mean score is \(avgScore)")
// Pass Swift code as a block
let scores = student.all_scores!
scores.call("each") { args in
print("Subject: \(args[0]) Score: \(args[1])")
return .nilObject
}
// Convert to a Swift array
let subjects = Array<String>(student.all_subjects!)
subjectsPopularityDb.submit(subjects: subjects)Bound class definition:
class Cell {
init() {
}
func setup(m: RbMethod) throws {
...
}
func getContent(m: RbMethod) throws -> String {
...
}
}
let cellClass = try Ruby.defineClass("Cell", initializer: Cell.init)
try cellClass.defineMethod("initialize",
argsSpec: RbMethodArgsSpec(mandatoryKeywords: ["width", "height"])
method: Cell.setup)
try cellClass.defineMethod("content",
argsSpec: RbMethodArgsSpec(requiresBlock: true),
method: Cell.getContent)Called from Ruby:
cell = Cell.new(width: 200, height: 100)
cell.content { |c| prettyprint(c) }Global variables:
// epochStore.current: Int
Ruby.defineGlobalVar("$epoch",
get: { epochStore.current },
set: { epochStore.current = newEpoch })Global functions:
let logArgsSpec = RbMethodArgsSpec(leadingMandatoryCount: 1,
optionalKeywordValues: ["priority" : 0])
try Ruby.defineGlobalFunction("log",
argsSpec: logArgsSpec) { _, method in
Logger.log(message: String(method.args.mandatory[0]),
priority: Int(method.args.keyword["priority"]!))
return .nilObject
}Calls from Ruby:
log(object_to_log)
log(object2_to_log, priority: 2)- Swift 6.0 or later, from swift.org or Xcode 16+
- macOS (tested on 14.1) or Linux (tested on Ubuntu Jammy)
- Ruby 2.6 or later including development files:
- For macOS, these come with Xcode.
- For Linux you may need to install a -dev package depending on how your Ruby is installed.
- RubyGateway requires 'original' MRI/CRuby Ruby - no JRuby/Rubinius/etc.
For macOS, if you are happy to use the system Ruby then you just need to include the RubyGateway framework as a dependency. If you are building on Linux or want to use a different Ruby then you also need to configure CRuby.
As of Swift 6, Apple have broken Swift PM such that you must pass "-Xcc -fmodules" to build the project. Check the CI invocation for an example.
Carthage for macOS:
github "johnfairh/RubyGateway"
Swift package manager for macOS or Linux:
.package(url: "https://github.com/johnfairh/RubyGateway", from: "6.0.0")
CRuby is the glue between RubyGateway and your Ruby installation. It is a separate github project but RubyGateway includes it as submodule so you do not install or require it separately.
By default it points to the macOS system Ruby. Follow the CRuby usage
instructions to change
this. For example on Ubuntu 18 using rbenv Ruby 3:
mkdir MyProject && cd MyProject
swift package init --type executable
vi Package.swift
# add RubyGateway as a package dependency (NOT CRuby)
# add RubyGateway as a target dependency
echo "import RubyGateway; print(Ruby.versionDescription)" > Sources/MyProject/main.swift
swift package update
swift package edit CRuby
Packages/CRuby/cfg-cruby --mode rbenv --name 3.0.0
PKG_CONFIG_PATH=$(pwd)/Packages/CRuby:$PKG_CONFIG_PATH swift run -Xcc -fmodulesWelcome: open an issue / [email protected] / @[email protected]
Distributed under the MIT license.