Do / with shorthand

Then.swift

import UIKit

public protocol Then {}

extension Then where Self: Any {
  
  /// Makes it available to set properties with closures just after initializing and copying the value types.
  ///
  ///     let frame = CGRect().with {
  ///       $0.origin.x = 10
  ///       $0.size.width = 100
  ///     }
  public func with(_ block: (inout Self) throws -> Void) rethrows -> Self {
    var copy = self
    try block(&copy)
    return copy
  }
  
  /// Makes it available to execute something with closures.
  ///
  ///     UserDefaults.standard.do {
  ///       $0.set("devxoul", forKey: "username")
  ///       $0.set("[email protected]", forKey: "email")
  ///       $0.synchronize()
  ///     }
  public func `do`(_ block: (Self) throws -> Void) rethrows {
    try block(self)
  }
  
}

extension Then where Self: AnyObject {
  
  /// Makes it available to set properties with closures just after initializing.
  ///
  ///     let label = UILabel().then {
  ///       $0.textAlignment = .Center
  ///       $0.textColor = UIColor.blackColor()
  ///       $0.text = "Hello, World!"
  ///     }
  public func then(_ block: (Self) throws -> Void) rethrows -> Self {
    try block(self)
    return self
  }
  
}

extension NSObject: Then {}

extension CGPoint: Then {}
extension CGRect: Then {}
extension CGSize: Then {}
extension CGVector: Then {}