Tutorial by Examples: on

Component attributes

[DisallowMultipleComponent] [RequireComponent( typeof( Rigidbody ) )] public class AttributesExample : MonoBehaviour { [...] } [DisallowMultipleComponent] The DisallowMultipleComponent attribute prevents users adding multiple instances of this component to one GameObject. [Requi...

unity3d • Attributes

Using .PHONY for non-files targets

Use .PHONY to specify the targets that are not files, e.g., clean or mrproper. Good example .PHONY: clean clean: rm *.o temp Bad example clean: rm *.o temp In the good example make knows that clean is not a file, therefore it will not search if it is or not up to date and will ex...

makefile • .PHONY target

Installation or Setup

Detailed instructions on getting core-bluetooth set up or installed.

core-bluetooth • Getting started with core-bluetooth

Drawing two rectangles on a

<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8" /> <title>Draw two rectangles on the canvas</title> <style> canvas{ border:1px solid gray; } </style> <script async...

HTML • Canvas

Multiple dependencies with the dependsOn method

You can add multiple dependencies. task A << { println 'Hello from A' } task B(dependsOn: A) << { println 'Hello from B' } task C << { println 'Hello from C' } task D(dependsOn: ['B', 'C'] << { println 'Hello from D' } The output is: >...

gradle • Task dependencies

Synchronous IPC communication

Create index.js as const {app, BrowserWindow, ipcMain} = require('electron') let win = null app.on('ready', () => { win = new BrowserWindow() win.loadURL(`file://${__dirname}/index.html`) win.webContents.openDevTools() win.on('closed', () => { win = null }) }) ipcM...

electron • Main and renderer process.

Installation and Setup

To install React Router, just run the npm command npm install --save react-router And you're done. This is literally all you have to do to install react router. Please Note : react-router is dependent on react, So make sure you install react as well. To set up: using an ES6 transpiler, like bab...

React Router • Getting started with React Router

Draw behind existing shapes with "destination-over"

context.globalCompositeOperation = "destination-over" "destination-over" compositing places new drawing under existing drawings. context.drawImage(rainy,0,0); context.globalCompositeOperation='destination-over'; // sunny UNDER rainy context.drawImage(sunny,0,0);

html5-canvas • Compositing

Erase existing shapes with "destination-out"

context.globalCompositeOperation = "destination-out" "destination-out" compositing uses new shapes to erase existing drawings. The new shape is not actually drawn -- it is just used as a "cookie-cutter" to erase existing pixels. context.drawImage(apple,0,0); conte...

html5-canvas • Compositing

Clip images inside shapes with "destination-in"

context.globalCompositeOperation = "destination-in" "destination-in" compositing clips existing drawings inside a new shape. Note: Any part of the existing drawing that falls outside the new drawing is erased. context.drawImage(picture,0,0); context.globalCompositeOperation...

html5-canvas • Compositing

Detect errors when writing a value on Android

There are many reasons a write operation may fail. A frequent one is because your security rules reject the operation, for example because you're not authenticated (by default a database can only be accessed by an authenticated user). You can see these security rule violations in the logcat output....

firebase • How do I listen for errors when accessing the database?

Notification Sound

Custom sounds may be provided for notifications generated by your app. When the system displays an alert for a local notification or badges an app icon, it plays this sound (so long as the user has not disabled notification sounds). The default value is nil which means no sound is played for your n...

iOS • UILocalNotification

Count the number of foreign relations

class Category(models.Model): name = models.CharField(max_length=20) class Product(models.Model): name = models.CharField(max_length=64) category = models.ForeignKey(Category, on_delete=models.PROTECT) To get the number products for each category: >>> categories = Ca...

Django • Model Aggregations

Atomic transactions

Problem By default, Django immediately commits changes to the database. When exceptions occur during a series of commits, this can leave your database in an unwanted state: def create_category(name, products): category = Category.objects.create(name=name) product_api.add_products_to_cate...

Django • Database transactions

Showing additional information when an exception occurs

It's important to handle exceptions in your service. When developing the service, you can set the WCF to provide more detailed information, adding this tag to configuration file, usually Web.config: <serviceDebug includeExceptionDetailInFaults="true"/> This tag must be placed w...

wcf • Handling exceptions

Throwing a user-friendly message with FaultException

You can handle exceptions and throw a most friendly message like 'Unavailable service' throwing a FaultException: try { // your service logic here } catch (Exception ex) { // You can do something here, like log the original exception throw new FaultException("There was a pro...

wcf • Handling exceptions

Throwing a FaultException with a Fault Code

The FaultException can also includes a FaultCode, that is a string data you can use to pass additional information, so the client can be able to distinguish different exceptions: try { // your service logic here } catch (Exception ex) { throw new FaultException("There was a proble...

wcf • Handling exceptions

Prime factorization

Example implementation of a prime factorization algorithm. A prime factorization algorithm will find for a given number n a list of primes, such that if you multiply those primes you get n. The below implementation will add -1 to the list of prime factors in case n < 0. Note that there exists no ...

math • prime numbers

One way: use a custom listener defined in your C# code

It took me a while to get this right, so I decided to share a solution because it might save someone else several days of trial and error. The problem: I want to be able to enable/disable WCF tracing in my C# .NET application and choose the trace output filename. I don't want users editing the .con...

wcf • How to: Disable/Enable WCF tracing in C# application code

implement View.OnLayoutChangeListener in Nativescript

let playerLayoutChangeListener = new android.view.View.OnLayoutChangeListener( { onLayoutChange : function ( v:View, left:number, top:number, right:number, bottom:number, oldLeft:number, oldTop:number, oldRight:number, oldBottom:number):any { if (left != oldLeft || top != oldTop ...

nativescript • implement Interface