Tutorial by Examples: en

Serial vs Concurrent Dispatch Queues

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...

iOS • GCD (Grand Central Dispatch)

Redirect special character with delayed expansion enabled

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 ^>>&...

batch-file • Input and output redirection

Compare frequencies across groups and remove legend title

g + geom_bar(aes(x = cut, fill = color), position = "fill") + guides(fill = guide_legend(title = NULL))

ggplot2 • Customizing axes, titles, and legends

Example UI Components

iOS • UIPheonix - easy, flexible, dynamic & highly scalable UI framework

Overload resolution with a large number of options

If you need to select between several options, enabling just one via enable_if<> can be quite cumbersome, since several conditions needs to be negated too. The ordering between overloads can instead be selected using inheritance, i.e. tag dispatch. Instead of testing for the thing that ne...

C++ • SFINAE (Substitution Failure Is Not An Error)

Vulnerable Approach: Concatenated SQL string with form references

This is the typical approach for novice developers building SQL action queries. They are vulnerable to the Bobby Tables type SQL Injection attacks. Dim strSQL As String strSQL = "INSERT INTO Employees chrFirstName, chrLastName, chrPhone " _ & "VALUES ('" & M...

ms-access • Parameterized Queries

Creating a podfile and installing a dependency

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'

cocoapods • Podfiles

Arguments lazy evaluation

Scala supports lazy evaluation for function arguments using notation: def func(arg: => String). Such function argument might take regular String object or a higher order function with String return type. In second case, function argument would be evaluated on value access. Please see the example...

Scala Language • Higher Order Function

Colorblind-friendly palettes

Even though colorblind people can recognize a wide range of colors, it might be hard to differentiate between certain colors. RColorBrewer provides colorblind-friendly palettes: library(RColorBrewer) display.brewer.all(colorblindFriendly = T) The Color Universal Design from the University ...

R Language • Color schemes for graphics

Apply custom font to Menu

public static void applyFontToMenu(Menu m, Context mContext){ for(int i=0;i<m.size();i++) { applyFontToMenuItem(m.getItem(i),mContext); } } public static void applyFontToMenuItem(MenuItem mi, Context mContext) { if(mi.hasSubMenu()) for(int i=0;i<mi.getSubMenu...

Android • Menu

Looking before you leap with processor-intensive function

A program can easily waste time by calling a processor-intensive function multiple times. For example, take a function which looks like this: it returns an integer if the input value can produce one, else None: def intensive_f(value): # int -> Optional[int] # complex, and time-consuming cod...

Python Language • Python Anti-Patterns

Custom mix task with command line arguments

In a basic implementation the task module must define a run/1 function that takes a list of arguments. E.g. def run(args) do ... end defmodule Mix.Tasks.Example_Task do use Mix.Task @shortdoc "Example_Task prints hello + its arguments" def run(args) do IO.puts "Hello ...

Elixir Language • Mix

Dynamically add component on specific event(click)

Main Component File: //our root app component import {Component, NgModule, ViewChild, ViewContainerRef, ComponentFactoryResolver, ComponentRef} from '@angular/core' import {BrowserModule} from '@angular/platform-browser' import {ChildComponent} from './childComp.ts' @Component({ selector: ...

Angular 2 • Dynamically add components using ViewContainerRef.createComponent

Open And Read From Stream File

Read the data of Create And Write To A Stream back into a program. with Ada.Streams.Stream_IO; procedure Main is -- -- ... same type definitions as in referenced example -- Fruit_Colors : array (Fruit) of Color; use Ada.Streams.Stream_IO; F : File_Type; X : Fruit...

ada • Files and I/O streams

Go to the End of the Month

Let's say we want to go to the last day of the month, this function will help on it: eom <- function(x, p=as.POSIXlt(x)) as.Date(modifyList(p, list(mon=p$mon + 1, mday=0))) Test: x <- seq(as.POSIXct("2000-12-10"),as.POSIXct("2001-05-10"),by="months") > da...

R Language • Date and Time

Move a date a number of months consistently by months

Let's say we want to move a given date a numof months. We can define the following function, that uses the mondate package: moveNumOfMonths <- function(date, num) { as.Date(mondate(date) + num) } It moves consistently the month part of the date and adjusting the day, in case the date re...