Kevin Johnson kevin49999

libdispatch efficiency tips

The libdispatch is one of the most misused API due to the way it was presented to us when it was introduced and for many years after that, and due to the confusing documentation and API. This page is a compilation of important things to know if you're going to use this library. Many references are available at the end of this document pointing to comments from Apple's very own libdispatch maintainer (Pierre Habouzit).

My take-aways are:

You should create very few, long-lived, well-defined queues. These queues should be seen as execution contexts in your program (gui, background work, ...) that benefit from executing in parallel. An important thing to note is that if these queues are all active at once, you will get as many threads running. In most apps, you probably do not need to create more than 3 or 4 queues.
Go serial first, and as you find performance bottle necks, measure why, and if concurrency helps, apply with care, always validating under system pressure. Reuse

Allow using optional binding to upgrade `self` from a weak to strong reference

Proposal: TBD
Author: Evan Maloney
Status: Draft
Review manager: TBD

Introduction

When working with escaping Swift closures, it is a common pattern to have the closure capture self weakly to avoid creating an object reference cycle.

Setup Godaddy Domain for GitHub Page

Create a new file CNAME and put the domain.com in the file.
Login GoDaddy > Manage domain > DNS Zone File.
Under A (Host) change @ point to 192.30.252.153.
Under CName (Alias) change www point to website.github.io.

	import Foundation

	enum LexingError: Error, Equatable {
	case syntaxError(String)
	case unexpectedEOF
	}

	enum ParsingError: Error {
	case expected(String)
	case unexpectedToken(Token)

	import SwiftUI

	extension View {
	func float<Content: View>(above: Content) -> ModifiedContent<Self, Above<Content>> {
	self.modifier(Above(aboveContent: above))
	}
	}

	struct Above<AboveContent: View>: ViewModifier {
	let aboveContent: AboveContent

	//
	// ContentView.swift
	// DeleteMe
	//
	// Created by Chris Eidhof on 02.02.21.
	//

	import SwiftUI

	/*

	package main

	import (
	"bytes"
	"encoding/base64"
	"fmt"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/credentials"
	"github.com/aws/aws-sdk-go/aws/session"

	import Foundation

	public protocol Cachable {
	var fileName: String { get }
	func transform() -> Data
	}

	final class Cacher {
	let destination: URL
	private let queue = OperationQueue()

	import Foundation

	class Cache<T: AnyObject>: NSCache {

	subscript(key: AnyObject) -> T? {
	get {
	return objectForKey(key)
	}
	set {
	if let value = newValue {

	const gblFrom = {
	year : 2020 ,
	month : 3,
	day : 29,
	hour : 0
	};
	const gblTo = {
	year : 2020 ,
	month : 8,
	day : 1,

Kevin Johnson kevin49999

libdispatch efficiency tips

Allow using optional binding to upgrade self from a weak to strong reference

Introduction

Setup Godaddy Domain for GitHub Page

Allow using optional binding to upgrade `self` from a weak to strong reference