VictorK filimo

Async/Await for Swift

Proposal: SE-XXXX
Authors: Chris Lattner, Joe Groff

Introduction

Modern Cocoa development involves a lot of asynchronous programming using closures and completion handlers, but these APIs are hard to use. This gets particularly problematic when many asynchronous operations are used, error handling is required, or control flow between asynchronous calls gets complicated. This proposal describes a language extension to make this a lot more natural and less error prone.

This paper introduces a first class Coroutine model to Swift. Functions can opt into to being async, allowing the programmer to compose complex logic involving asynchronous operations, leaving the compiler in charge of producing the necessary closures and state machines to implement that logic.

NOTE (2022-07-09): Xcode finally added this functionality in Xcode 14, please see release notes here:

New Features in Xcode 14 Beta 3
When editing code, the Edit > Duplicate menu item and its corresponding keyboard shortcut now duplicate the selected text — or the line that currently contains the insertion point, if no text is selected. (8614499) (FB5618491)

Xcode line duplicate

Bind keys to duplicate lines in Xcode

An important goal in Swift is clarity at the point of use, this appears in the API Design Guidelines as a fundamental, but also pervades the design of the Swift language itself.

I think that removing the where clause from Swift's for loops reduces clarity.

It may be that there are other ways to express the same code result, but "only one way to do it" has never been a Swift goal that I'm aware of, and an identical result does not necessarily equate to an identical intent.

Consider the following, which was actually a source of brief confusion for me while reading some of your code.

Example 1:

Руководство по оформлению Markdown файлов

Markdown - это облегчённый язык разметки, который преобразует текст в структурированный HTML. Следующее руководство поможет вам разобраться, как использовать Markdown.

Заголовки

# Заголовок первого уровня
## Заголовок второго уровня
### Заголовок третьего уровня
#### Заголовок четвёртого уровня
##### Заголовок пятого уровня

Comparison of ASP.NET and Node.js for Backend Programming

We will compare ASP.NET and Node.js for backend programming.
Source codes from examples.

Updates

This document was published on 21.09.2015 for a freelance employer. Some changes since then (14.02.2016):

Koa.js no longer uses co-routines, it has switched to Babel's async/await. yield and await are used almost in the same way, so I see no point to rewrite the examples.

	/* 1. Class Constant : Lazy initialization is supported. Officially recommanded way */

	class Singleton {
	static let shared = Singleton()
	private init() { } // prevent creating another instances.
	}

	/* 2. Nested Struct : Workaround for the lack of static class constants in Swift 1.1 and earlier. still useful
	in functions, where static constants and varialbles cannot be used. */

	// https://stackoverflow.com/a/45777692/5536516

	import Foundation

	struct MemoryAddress<T>: CustomStringConvertible {

	let intValue: Int

	var description: String {
	let length = 2 + 2 * MemoryLayout<UnsafeRawPointer>.size

	# after appcleaner does his magic, do this

	sudo rm -rf "/Library/Application Support/Paragon Software/"
	sudo rm /Library/LaunchDaemons/com.paragon-software.installer.plist
	sudo rm /Library/LaunchDaemons/com.paragon-software.ntfs.loader.plist
	sudo rm /Library/LaunchDaemons/com.paragon-software.ntfsd.plist
	sudo rm /Library/LaunchAgents/com.paragon-software.ntfs.notification-agent.plist
	sudo rm -rf /Library/Filesystems/ufsd_NTFS.fs/
	sudo rm -rf /Library/PrivilegedHelperTools/com.paragon-software.installer
	sudo rm -rf /Library/Extensions/ufsd_NTFS.kext/

	enum HTTPStatusCodes: Int {
	// 100 Informational
	case Continue = 100
	case SwitchingProtocols
	case Processing
	// 200 Success
	case OK = 200
	case Created
	case Accepted
	case NonAuthoritativeInformation

	// WastingTimeOnStackOverflowTests.swift Created by mason on 2016-09-18.

	import XCTest

	/// Measures performance of two different ways of checking whether an index is valid
	/// for a given array (the variable "a" is an array of 1,000,000 unique strings, and
	/// "val" is the index to be checked):
	///
	/// a.indices.contains(val)
	/// vs: