Orcam - A Collection of Useful Swift Macros

This is a collection of useful Swift macros

Prerequisites

• Xcode 15 or higher
• Swift 5.9

Installation

Swift Package Manager

Once you have your Swift package set up, adding orcam as a dependency to the dependencies value in Package.swift.

.package(url: "https://github.com/trinhngocthuyen/orcam", from: "0.0.1")

Then, add Orcam module product as a dependency of a target's dependencies.

.product(name: "Orcam", package: "orcam")

Features

@Init - Generate the member-wise init of a struct/class

@Init
class Foo {
  let x: Int
  let y: Double?
  let completion: () -> Void
}

Expanded code

class Foo {
  let x: Int
  let y: Double?
  let completion: () -> Void

  init(x: Int, y: Double? = nil, completion: @escaping () -> Void) {
    self.x = x
    self.y = y
    self.completion = completion
  }
}

@Singleton - Generate the Singleton code of a struct/class

@Singleton
class Foo {
}

Expanded code

class Foo {
  static let shared = Foo()

  private init() {
  }
}

The macro still works when we explicitly declare the shared variable.

@Singleton
class Foo {
  let x: Int

  static let shared = Foo(x: 0)
}

@Copyable - Generate the copy function of a struct/class with updated properties

@Copyable
struct Foo {
  let x: Int
  let y: Int
}

Expanded code

struct Foo {
  let x: Int
  let y: Int

  func copy(x: Int? = nil, y: Int? = nil) -> Self {
    return .init(x: x ?? self.x, y: y ?? self.y)
  }
}

This macro also generates a copy function in which each property can be updated with a closure. To enable this, pass the argument closure as true to the macro.

@Copyable(closure: true)
struct Foo {
  let x: Int
  let y: Int
}

Expanded code

struct Foo {
  let x: Int
  let y: Int

  func copy(x: Int? = nil, y: Int? = nil) -> Self {
    return .init(x: x ?? self.x, y: y ?? self.y)
  }

  func copy(update_x: ((Int) -> Int)? = nil, update_y: ((Int) -> Int)? = nil) -> Self {
    func call<V>(_ f: ((V) -> V)?, _ v: V) -> V {
      f?(v) ?? v
    }
    return .init(x: call(update_x, self.x), y: call(update_y, self.y))
  }
}