Tutorial by Examples: re

Common Lisp REPL is an interactive environment. Every form written after the prompt is evaluated, and its value is afterwards printed as result of the evaluation. So the simplest possible “Hello, World!” program in Common Lisp is: CL-USER> "Hello, World!" "Hello, World!" CL...

Creating and configuring Sprite and TextField objects at runtime can be costly if you are creating hundreds of thousands of these on a single frame. Therefore a common trick is "pooling" these objects for later reuse. Remember we are not just trying to optimize the creation time (new Sprit...

class Person(models.Model): name = models.CharField(max_length=50) description = models.TextField() class Club(models.Model): name = models.CharField(max_length=50) members = models.ManyToManyField(Person) Here we define a relationship where a club has many Persons and memb...

UITextView has built in support to auto detect a variety of data. The data that is able to be auto-detected currently includes: enum { UIDataDetectorTypePhoneNumber = 1 << 0, UIDataDetectorTypeLink = 1 << 1, UIDataDetectorTypeAddress = 1 << 2, UID...

In F#, all functions take exactly one parameter. This seems an odd statement, since it's trivially easy to declare more than one parameter in a function declaration: let add x y = x + y But if you type that function declaration into the F# interactive interpreter, you'll see that its type signat...

It is possible to find the first element of a Stream that matches a condition. For this example, we will find the first Integer whose square is over 50000. IntStream.iterate(1, i -> i + 1) // Generate an infinite stream 1,2,3,4... .filter(i -> (i*i) > 50000) // Filter to find element...

Variables can be incremented or decremented by 1 with ++ or --, respectively. They can either precede or succeed variables and slightly vary semantically, as shown below. $i = 1; echo $i; // Prints 1 // Pre-increment operator increments $i by one, then returns $i echo ++$i; // Prints 2 // P...

Files: - example.rs (root of our modules tree, generally named lib.rs or main.rs when using Cargo) - first.rs - second/ - mod.rs - sub.rs Modules: - example -> example - first -> example::first - second -> example::second - sub -> exampl...

It's fairly common that you may create a class that implements IDisposable, and then derive classes that also contain managed resources. It is recommendeded to mark the Dispose method with the virtual keyword so that clients have the ability to cleanup any resources they may own. public class Paren...

Streams of elements usually do not allow access to the index value of the current item. To iterate over an array or ArrayList while having access to indexes, use IntStream.range(start, endExclusive). String[] names = { "Jon", "Darin", "Bauke", "Hans", "M...

An interesting thing to note which may help optimize your applications is that primitives are actually also refcounted under the hood. Let's take a look at numbers; for all integers between -5 and 256, Python always reuses the same object: >>> import sys >>> sys.getrefcount(1) 7...

>>> import sys >>> a = object() >>> sys.getrefcount(a) 2 >>> b = a >>> sys.getrefcount(a) 3 >>> del b >>> sys.getrefcount(a) 2

Install haveged (example sudo apt-get install haveged) to speed up the random byte process. Then: gpg --gen-key gpg --list-keys outputs: pub 2048R/NNNNNNNN 2016-01-01 uid Name <[email protected]> sub 2048R/xxxxxxxx 2016-01-01 Then publish: gpg --keyserver pgp.mi...

Aggregation operations computes a single value from a collection of values. Aggregate Performs a custom aggregation operation on the values of a collection. Method Syntax // Aggregate var numbers = new int[] { 1, 2, 3, 4, 5 }; var product = numbers.Aggregate(1, (acc, n) => acc * n);...

<rect> represents rectangle, apart from aesthetic properties like stroke and fill, rectangle shall be defined by location and size. As for the location, it is determined by the x and y attributes. The location is relative to the rectangle’s parent. And if you don’t specify the x or y attribut...

Components in Vue are like widgets. They allow us to write reusable custom elements with desired behavior. They are nothing but objects which can contain any/all of the options that the root or any Vue instance can contain, including an HTML template to render. Components consist of: HTML marku...

When you bind a service to your application credentials become available through the VCAP_SERVICES environment variable. This environment variable contains JSON containing the credentials for all bound services. Example VCAP_SERVICES environment variable { "push-reappt": [ { ...

String#replace can have a function as its second argument so you can provide a replacement based on some logic. "Some string Some".replace(/Some/g, (match, startIndex, wholeString) => { if(startIndex == 0){ return 'Start'; } else { return 'End'; } }); // will retur...

nginx consists of modules which are controlled by directives specified in the configuration file. Simple Directives A simple directive consists of the name and parameters separated by spaces and ends with a semicolon (;). Block Directive A block directive has the same structure as a simple direc...

Preface You'll need node >= 4 and express 4 for this project. You can get the latest node distribution from their download page. Before this tutorial, you should initialize your node project by running $ npm init from the command line and filling in the information you want. Note that you c...