Tutorial by Examples: en

Enumerating the Enumerable

The IEnumerable<T> interface is the base interface for all generic enumerators and is a quintessential part of understanding LINQ. At its core, it represents the sequence. This underlying interface is inherited by all of the generic collections, such as Collection<T>, Array, List<T&g...

C# Language • LINQ Queries

Existential Operator

CoffeeScript's existential operator ? check if the variable is null or undefined. 1. Check for null or undefined. alert "Hello CoffeeScript!" if myVar? javascript equivalent: if (typeof myVar !== "undefined" && myVar !== null) { alert("Hello CoffeeScript!&qu...

coffeescript • Operators

Send form parts and listen to the request

Makes a request only sending part of the form. The text1 value is set, but not text2, as the listener states. Bean.java @ManagedBean @ViewScoped public class Bean { private String text1; private String text2; public String getText1() { return text1; } pu...

jsf • Ajax Integration

Ajax on javascript event

The date is updated whenever user types on the input field: Bean.java @ManagedBean @ViewScoped public class Bean { public Date getCurrentDate(){ return new Date(); } } sample.xhtml <html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://x...

jsf • Ajax Integration

Convenient in-model sanitizing

Set a convenience method in your base model namespace Base; class Model extends \Phalcon\Mvc\Model { public function sanitize($attr, $filterName) { $filter = $this->getDI()->get('filter'); $this->$attr = $filter->sanitize($this->$attr, $filterName); ...

phalcon • Filtering and Sanitizing

Local Type Inference

Scala has a powerful type-inference mechanism built-in to the language. This mechanism is termed as 'Local Type Inference': val i = 1 + 2 // the type of i is Int val s = "I am a String" // the type of s is String def squared(x : Int) = x*x // the return type ...

Scala Language • Type Inference

Type Inference And Generics

The Scala compiler can also deduce type parameters when polymorphic methods are called, or when generic classes are instantiated: case class InferedPair[A, B](a: A, b: B) val pairFirstInst = InferedPair("Husband", "Wife") //type is InferedPair[String, String] // Equiv...

Scala Language • Type Inference

Limitations to Inference

There are scenarios in which Scala type-inference does not work. For instance, the compiler cannot infer the type of method parameters: def add(a, b) = a + b // Does not compile def add(a: Int, b: Int) = a + b // Compiles def add(a: Int, b: Int): Int = a + b // Equivalent expression, compiles ...

Scala Language • Type Inference

length([String])

Returns the number of characters of the given String Considerations If a number is given instead a String, the result will be the length of the String representing the given number. I.e. If we execute length(12345) the result will be the same as length("12345"), that is 5 If...

awk • Built-in functions

Assignment

To assign a value to a previously declared variable, use the assignment operator, =: a = 6; b = "Foo"; As an alternative to independent declaration and assignment, it is possible to perform both steps in one statement: var a = 6; let b = "Foo"; It is in this syntax that...

JavaScript • Declarations and Assignments

Creating a Twig_Extension

You can group all your custom functions/filters/tests/... inside a custom Twig_Extension class: ProjectTwigExtension class ProjectTwigExtension extends Twig_Extension { public function getFunctions() { return array( new Twig_SimpleFunction('twig_function_name', array($...

twig • Extending twig

Multi-line comments cannot be nested

In C, multi-line comments, /* and */, do not nest. If you annotate a block of code or function using this style of comment: /* * max(): Finds the largest integer in an array and returns it. * If the array length is less than 1, the result is undefined. * arr: The array of integers to search....

C Language • Common pitfalls

Representation of signed integers

Each signed integer type may be represented in any one of three formats; it is implementation-defined which one is used. The implementation in use for any given signed integer type at least as wide as int can be determined at runtime from the two lowest-order bits of the representation of value -1 ...

C Language • Implementation-defined behaviour

When to use a defer statement

A defer statement consists of a block of code, which will be executed when a function returns and should be used for cleanup. As Swift's guard statements encourage a style of early return, many possible paths for a return may exist. A defer statement provides cleanup code, which then does not need ...

Swift Language • The Defer Statement

When NOT to use a defer statement

When using a defer-statement, make sure the code remains readable and the execution order remains clear. For example, the following use of the defer-statement makes the execution order and the function of the code hard to comprehend. postfix func ++ (inout value: Int) -> Int { defer { value...

Swift Language • The Defer Statement

ImageView ScaleType - Center

The image contained in the ImageView may not fit the exact size given to the container. In that case, the framework allows you to resize the image in a number of ways. Center <ImageView android:layout_width="20dp" android:layout_height="20dp" andr...

Android • ImageView

ImageView ScaleType - CenterCrop

Scale the image uniformly (maintain the image's aspect ratio) so that both dimensions (width and height) of the image will be equal to or larger than the corresponding dimension of the view (minus padding). Official Docs When the image matches the proportions of the container: When the image is...

Android • ImageView

ImageView ScaleType - CenterInside

Scale the image uniformly (maintain the image's aspect ratio) so that both dimensions (width and height) of the image will be equal to or less than the corresponding dimension of the view (minus padding). Official Docs It will center the image and resize it to the smaller size, if both container s...

Android • ImageView

ImageView ScaleType - FitStart and FitEnd

Scale the image using START. Scale the image using END. Official Docs FitStart This will fit to the smallest size of the container, and it will align it to the start. <ImageView android:layout_width="200dp" android:layout_height="200dp" android:src...

Android • ImageView

ImageView ScaleType - FitCenter

Scale the image using CENTER. Official Docs This expands the image to try to match the container and it will align it to the center, it will fit to the smaller size. Bigger height ( fit to width ) Same width and height.

Android • ImageView