Scope

Scoping Functions of Swift Style for Readable Code

🌷 Usage

apply, also , let, with, run

Reture Value

The scope functions differ by the result they return:

• apply, also return the context object.
• let, with, and run return the closure result.

The return value of also and apply is the context object itself. so they can be included into call chains as side steps.

let org = Organization()
  .also { print("new podo org") }
  .apply {
    $0.name = "podo"
    $0.member = Member(name: "jayce", role: .owner)
  }

They also can be used in return statements of functions returning the context object.

func newPodoOrg() -> Organization {
  Organization().apply {
    $0.name = "podo"
    $0.member = Member(name: "jayce", role: .owner)
  }
}

apply

Use apply for code blocks that don't return a value and mainly operate on the members of the receiver object.

let org = Organization().apply {
  $0.name = "podo"
  $0.member = Member(name: "jayce", role: .owner)
}
print(org)

also

Use also for additional actions that don't alter the object, such as logging or printing debug information.

let member = Member(name: "jayce", role: .owner)
let org = Organization()

org.also { print("new member") }
  .addMember(member)

let

let can be used to invoke one or more functions on result of call chains.

let numbers = [1, 5, 10]
numbers.map { $0 * 2 }
  .filter { $0 > 3}
  .let { $0.count }

let is often used for executing a code block only with non-nil values.

var org: Organization?
org = Organization(name: "podo", member: Member(name: "jayce", role: .member))

org?.member?.let {
  $0.role = .owner // $0 is not nil inside '?.let {}' 
}

with

A non-extension function: the context object is passed as an argument, and return value is the closure result.

with can be read as "with this object, do the following."

let description = with(org) {
  "Orgnaization name is \($0.name), "
    .appending("member name is \($0.member.name)")
}
print(description)

run

Use run as a non-extension function. Non-extension run lets you execute a block of several statements where an expression is required.

let hexNumberRegex = run { () -> Regex in
  let digits = "0-9"
  let hexDigits = "A-Fa-f"
  let sign = "+-"

  return Regex("[\(sign)]?[\(digits)\(hexDigits)]+")
}

⚙️ Installation

• Using Swift Package Manager

  import PackageDescription
  
  let package = Package(
    name: "MyApp",
    dependencies: [
      .package(url: "https://github.com/hb1love/Scope", .upToNextMajor(from: "2.1.0"))
    ]
  )

• Using CocoaPods

  pod 'Scope'

👮‍ License

Scope is available under the MIT license. See the LICENSE for details.