Tutorial by Examples: co

Singleton Objects Scala supports static members, but not in the same manner as Java. Scala provides an alternative to this called Singleton Objects. Singleton objects are similar to a normal class, except they can not be instantiated using the new keyword. Below is a sample singleton class: object...

During development, when certain code paths must be prevented from the reach of control flow, you may use assert(0) to indicate that such a condition is erroneous: switch (color) { case COLOR_RED: case COLOR_GREEN: case COLOR_BLUE: break; default: assert(0); ...

Declaration and usage. // a is const int, so it can't be changed const int a = 15; a = 12; // Error: can't assign new value to const variable a += 1; // Error: can't assign new value to const variable Binding of references and pointers int &b = a; // Error: ca...

int a = 0, b = 2; const int* pA = &a; // pointer-to-const. `a` can't be changed through this int* const pB = &a; // const pointer. `a` can be changed, but this pointer can't. const int* const pC = &a; // const pointer-to-const. //Error: Cannot assign to a const reference *pA = b...

The = operator is used for assignment. The == operator is used for comparison. One should be careful not to mix the two. Sometimes one mistakenly writes /* assign y to x */ if (x = y) { /* logic */ } when what was really wanted is: /* compare if x is equal to y */ if (x == y) { ...

Be careful with semicolons. Following example if (x > a); a = x; actually means: if (x > a) {} a = x; which means x will be assigned to a in any case, which might not be what you wanted originally. Sometimes, missing a semicolon will also cause an unnoticeable problem: if (i &lt...

Log into a running container A user can enter a running container in a new interactive bash shell with exec command. Say a container is called jovial_morse then you can get an interactive, pseudo-TTY bash shell by running: docker exec -it jovial_morse bash Log into a running container with a s...

Collection initialization syntax can be used when instantiating any class which implements IEnumerable and has a method named Add which takes a single parameter. In previous versions, this Add method had to be an instance method on the class being initialized. In C#6, it can also be an extension me...

The two possible ways of issuing a context.become (replacing or adding the new behavior) are offered separately to enable a clutter-free notation of nested receives: val a = actor(new Act { become { // this will replace the initial (empty) behavior case "info" ⇒ sender() ! "A...

Open Control Panel -> Programs and Features, choose the Visual Studio 2015 item, and then choose the Change button. In the setup wizard for Visual Studio, choose the Modify button. In the list of optional features to install, select the HTML/JavaScript (Apache Cordova) checkbox, c...

In Visual Studio, choose Tools->Extensions and Updates. In the Updates tab of the Extensions and Updates dialog box, choose Product Updates. If an update for Visual Studio Tools for Apache appears, select it, and then choose the Update button.

First you create a new Cordova project: cordova create HelloWorld my.application.identifier AppName This will create a blank Cordova project in the HelloWorld folder with identifier my.application.identifier (which should be unique for each application) with name AppName. Next you add th...

<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"> <path d="M 10,10 L 100,50" stroke="blue" stroke-width="5" /> </svg> Result:

<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"> <path d="M 10,10 H 200" stroke="orange" stroke-width="5" /> </svg> Result:

<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"> <path d="M 10,10 l 90,90 M 100,10 l -90,90" stroke="red" stroke-width="10" /> </svg> Result:

<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"> <path d="M 10,10 V 200" stroke="green" stroke-width="5" /> </svg> Result:

The goal with using anonymous structs is to decode only the information we care about without littering our app with types that are used only in a single function. jsonBlob := []byte(` { "_total": 1, "_links": { "self": "https://api.twitch.tv/k...

Code lens is a simple way to know what happens with the code. Here you could find an image with the number of references of a method or class. If you can't see the code lens please see this question: Missing CodeLens references count in VS 2015 Community edition

Initialize a UICollectionView with a CGRect frame: Swift: let collection = UICollectionView(frame: CGRect(x: 0, y: 0, width: 200, height: 21)) Objective C: UICollectionView *collection = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 0, 200, 21)]; You can also create a UICollectionVi...

Every collection view must have a Datasource object. The Datasource object is the content that your app will display within the UICollectionView. At a minimum, all Datasource objects must implement the collectionView:numberOfItemsInSection: and collectionView:cellForItemAtIndexPath: methods. Requir...