Tutorial by Examples: d

Default vs OnPush

Consider the following component with one input myInput and an internal value called someInternalValue. Both of them are used in a component's template. import {Component, Input} from '@angular/core'; @Component({ template:` <div> <p>{{myInput}}</p> <p>{...

Angular 2 • Optimizing rendering using ChangeDetectionStrategy

Changing Method Visibility

trait HelloWorld { public function sayHello() { echo 'Hello World!'; } } // Change visibility of sayHello class MyClass1 { use HelloWorld { sayHello as protected; } } // Alias method with changed visibility // sayHello visibility not changed class MyClass2 { u...

PHP • Traits

Decomposition

Any array can be quickly decomposed by assigning its elements into multiple variables. A simple example: arr = [1, 2, 3] # --- a = arr[0] b = arr[1] c = arr[2] # --- or, the same a, b, c = arr Preceding a variable with the splat operator (*) puts into it an array of all the elements that h...

Ruby Language • Arrays

Munging during expansion

Variables don't necessarily have to expand to their values - substrings can be extracted during expansion, which can be useful for extracting file extensions or parts of paths. Globbing characters keep their usual meanings, so .* refers to a literal dot, followed by any sequence of characters; it's ...

Bash • Bash Parameter Expansion

Feed a while loop with the output of a command

This feeds a while loop with the output of a grep command: while IFS=":" read -r user _ do # "$user" holds the username in /etc/passwd done < <(grep "hello" /etc/passwd)

Bash • Process substitution

Passing data to FXML - accessing existing controller

Problem: Some data needs to be passed to a scene loaded from a fxml. Solution Specify a controller using the fx:controller attribute and get the controller instance created during the loading process from the FXMLLoader instance used to load the fxml. Add methods for passing the data to the contr...

javafx • FXML and Controllers

Passing data to FXML - Specifying the controller instance

Problem: Some data needs to be passed to a scene loaded from a fxml. Solution Set the controller using the FXMLLoader instance used later to load the fxml. Make sure the controller contains the relevant data before loading the fxml. Note: in this case the fxml file must not contain the fx:contro...

javafx • FXML and Controllers

Creating a new query using LinqPad

LinqPad is a great tool that allows you to learn and test features of .Net languages (C#, F# and VB.Net.) Install LinqPad Create a new Query (Ctrl + N) Under language, select "C# statements" Type the following code and hit run (F5) string hw = "Hello World&quo...

C# Language • Getting started with C# Language

Get started

index.html <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Trying out ports</title> </head> <body> <div id="app"></div> <script src="elm.js"></script> ...

Elm Language • Ports (JS interop)

Keyword-only and Keyword-required arguments

Python 3 allows you to define function arguments which can only be assigned by keyword, even without default values. This is done by using star * to consume additional positional parameters without setting the keyword parameters. All arguments after the * are keyword-only (i.e. non-positional) arg...

Python Language • *args and **kwargs

Customizing TableCell look depending on item

Sometimes a column should show different content than just the toString value of the cell item. In this case the TableCells created by the cellFactory of the TableColumn is customized to change the layout based on the item. Important Note: TableView only creates the TableCells that are shown in the...

javafx • TableView

Convert all columns of a data.frame to character class

A common task is to convert all columns of a data.frame to character class for ease of manipulation, such as in the cases of sending data.frames to a RDBMS or merging data.frames containing factors where levels may differ between input data.frames. The best time to do this is when the data is read ...

R Language • Data frames

Installation and Setup

Ubuntu On recent Ubuntu versions, you can install an up-to-date version of CouchDB with sudo apt-get install couchdb. For older versions, such as Ubuntu 14.04, you should run: sudo add-apt-repository ppa:couchdb/stable -y sudo apt-get update sudo apt-get install couchdb -y Fedora To install ...

couchdb • Getting started with couchdb

Block DO construct

A do construct is a looping construct which has a number of iterations governed by a loop control integer i do i=1, 5 print *, i end do print *, i In the form above, the loop variable i passes through the loop 5 times, taking the values 1 to 5 in turn. After the construct has completed th...

Fortran • Execution Control

Queue Driver Configuration

Each of Laravel's queue drivers are configured from the config/queue.php file. A queue driver is the handler for managing how to run a queued job, identifying whether the jobs succeeded or failed, and trying the job again if configured to do so. Out of the box, Laravel supports the following queue ...

Laravel • Queues

Setting parameters for PreparedStatement

Placeholders in the query string need to be set by using the set* methods: String sql = "SELECT * FROM EMP WHERE JOB = ? AND SAL > ?"; //Create statement to make your operations PreparedStatement statement = connection.prepareStatement(sql); statement.setString(1, "MANAGER&...

jdbc • PreparedStatement

Simple Dual Port RAM

Simple Dual Port RAM with separate addresses and clocks for read/write operations. module simple_ram_dual_clock #( parameter DATA_WIDTH=8, //width of data bus parameter ADDR_WIDTH=8 //width of addresses buses )( input [DATA_WIDTH-1:0] data, //da...

verilog • Memories

Validating User Account On Publish

Sometimes it's a good idea to further secure your publishes by requiring a user login. Here is how you achieve this via Meteor. import { Recipes } from '../imports/api/recipes.js'; import { Meteor } from 'meteor/meteor'; Meteor.publish('recipes', function() { if(this.userId) { return Re...

meteor • Publishing Data

decimal literals

decimal literals are defined by using the suffix M or m on a real number: decimal m = 30.5M;

C# Language • Literals

double literals

double literals are defined by using the suffix D or d, or by using a real number: double d = 30.5D;

C# Language • Literals