Tutorial by Examples: di

DispatchSemaphore provides an efficient implementation of a traditional counting semaphore, which can be used to control access to a resource across multiple execution contexts. A scenario for when to use a semaphore could be if you are doing some file reading/writing, if multiple tasks are t...

There are two main functions in Redis (HSET and HMSET) for adding fields to a hash key. Both functions are available in redis-py. Using HSET: import redis r = redis.StrictRedis(host='myserver', port=6379, db=0) r.hset('my_key', 'field0', 'value0') Using HMSET: import redis r = redis.St...

Swift 3 Serial Queue func serialQueues () { let serialQueue = DispatchQueue(label: "com.example.serial") //default queue type is a serial queue let start = Date () for i in 0...3 { //launch a bunch of tasks serialQueue.a...

This example echoes the special character ! into a file. This would only work when DelayedExpansion is disabled. When delayed expansion in enabled, you will need to use three carets and an exclamation mark like this: @echo off setlocal enabledelayedexpansion echo ^^^!>file echo ^>>&...

Redis allows you to add items to either the right or the left of a list. If I was working with a list, my_list and I wanted to prepend 3 to the list, I could do that using the Redis LPUSH command: LPUSH my_list 3 If I wanted to append 3 to my_list, I would instead use the RPUSH command: RPUSH ...

The basic Redis command for adding an item to a set is SADD. It takes a key and one or more members and adds them to the set stored at the given key. For example, lets say that I wanted to create a set with the items apple, pear and banana. I could execute either of the following: SADD fruit app...

Redis provides the ZADD command to add items to a sorted set. The basic form of the ZADD command is to specify the set, the item to add and it's score. For example, if I wanted to construct an ordered set of my favorite food (from least to most), I could use either of: zadd favs 1 apple zadd fav...

/** * Resizes an image using a Graphics2D object backed by a BufferedImage. * @param srcImg - source image to scale * @param w - desired width * @param h - desired height * @return - the new resized image */ private BufferedImage getScaledImage(Image srcImg, int w, int h){ //Cre...

Be aware that the WebBrowser control is not sympathetic to your XAML definition, and renders itself over the top of other things. For example, if you put it inside a BusyIndicator that has been marked as being busy, it will still render itself over the top of that control. The solution is to bind th...

In the directory if the xcodeproj, create a new file called Podfile. The following is an example of a Podfile that installs the pod 'AFNetworking' version 1.0 to the app MyApp. target 'MyApp' pod 'AFNetworking', '~> 1.0'

In the tsconfig.json set "sourceMap": true, to generate mappings alongside with js-files from the TypeScript sources using the tsc command. The launch.json file: { "version": "0.2.0", "configurations": [ { "type"...

Add ts-node to your TypeScript project: npm i ts-node Add a script to your package.json: "start:debug": "ts-node --inspect=5858 --debug-brk --ignore false index.ts" The launch.json needs to be configured to use the node2 type and start npm running the start:debug script: ...

extension Dictionary { func merge(dict: Dictionary<Key,Value>) -> Dictionary<Key,Value> { var mutableCopy = self for (key, value) in dict { // If both dictionaries have a value for same key, the value of the other dictionary is used. mu...

The XAML file for the spirograph parameters is below. It includes three text boxes for the spirograph parameters and a group of three radio buttons for color. When we give radio buttons the same group name - as we have here - WPF handles the on/off switching when one is selected. <!-- This fi...

Transcript show: 'Hello World!'. This will print Hello World! to the Transcript window in Smalltalk. Transcript is the class that allows you to print to the Transcript window by sending the message show: to that object. The colon indicates that this message requires a parameter which is in this c...

ng new NewProject or ng init NewProject

import sys from PyQt5.QtWidgets import QApplication, QWidget from PyQt5.QtGui import QIcon class Example(QWidget): def __init__(self): super().__init__() self.initUI() def initUI(self): self.setGeometry(300, 30...

#define kPaperSizeA4 CGSizeMake(595.2,841.8) First of all implement UIPrintPageRenderer protocol @interface UIPrintPageRenderer (PDF) - (NSData*) printToPDF; @end @implementation UIPrintPageRenderer (PDF) - (NSData*) printToPDF { NSMutableData *pdfData = [NSMutableData data]; ...

Given an 'albums' collection, an item can be added by creating a file in the <source>/_albums directory. Note that files not including frontmatter will be ignored. For instance, adding a file called my_album.md to the _albums directory would add it to the collection: --- title: "My Alb...

fs is the File System API in node. We can use the method readFile on our fs variable, pass it a data.csv file, format and function that reads and splits the csv for further processing. This assumes you have a file named data.csv in the same folder. 'use strict' const fs = require('fs'); fs.r...