Tutorial by Examples: n

Synchronization Primitive: Event

Concept Use an Event to synchronize the scheduling of multiple coroutines. Put simply, an event is like the gun shot at a running race: it lets the runners off the starting blocks. Example import asyncio # event trigger function def trigger(event): print('EVENT SET') event.set() #...

Python Language • Asyncio Module

Installing Electrify for a Meteor application

Electron ports HTML web applications to native applications for a range of devices, including creating native desktop applications. It's also very easy to get started! To begin, we must have electron, nodejs, npm, git and meteor installed. Familiarity with these tools is vital for working with Mete...

meteor • Electrify - Compiling Meteor as a Locally Installable App

Using Electrify on a Meteor Application

Let's download a Meteor Todos example project, using a Linux shell (command line) script, to test out Electrifying a project for the first time: Requirements for this section: Git apt-get install git-all There are many ways to install Git. Check them out here. git is a version control sys...

meteor • Electrify - Compiling Meteor as a Locally Installable App

Avoiding gaps in tables used as arrays

Defining our terms By array here we mean a Lua table used as a sequence. For example: -- Create a table to store the types of pets we like. local pets = {"dogs", "cats", "birds"} We're using this table as a sequence: a group of items keyed by integers. Many langua...

Lua • Tables

Installation or Setup

Installing Angular Material npm npm install angular-material --save bower bower install angular-material --save jspm jspm install angular-material From Cloud cdnjs | jsdelivr | googlecdn Getting Started (blank shell) <html lang="en"> <head> <meta name...

angular-material • Getting started with angular-material

Integer Conversions in Function Calls

Given that the function has a proper prototype, integers are widened for calls to functions according to the rules of integer conversion, C11 6.3.1.3. 6.3.1.3 Signed and unsigned integers When a value with integer type is converted to another integer type other than _Bool, if the value can be r...

C Language • Implicit and Explicit Conversions

Pointer Conversions in Function Calls

Pointer conversions to void* are implicit, but any other pointer conversion must be explicit. While the compiler allows an explicit conversion from any pointer-to-data type to any other pointer-to-data type, accessing an object through a wrongly typed pointer is erroneous and leads to undefined beh...

C Language • Implicit and Explicit Conversions

In an inherited class with managed resources

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...

C# Language • IDisposable interface

Synchronously executing asynchronous NPM methods w/ callbacks.

This example wraps the asynchronous method oauth2.client.getToken(callback) from the package NPM package simple-oauth2into a Fiber so that the method may be called synchronously. const oauth2 = require('simple-oauth2')(credentials); const credentials = { clientID: '#####', clientSecret...

meteor • Wrapping asynchronous methods into a Fiber for synchronous execution.

GroupJoin with outer range variable

Customer[] customers = Customers.ToArray(); Purchase[] purchases = Purchases.ToArray(); var groupJoinQuery = from c in customers join p in purchases on c.ID equals p.CustomerID into custPurchases select new { CustName = c.Name, custPurchases }; ...

C# Language • LINQ Queries

ElementAt and ElementAtOrDefault

ElementAt will return the item at index n. If n is not within the range of the enumerable, throws an ArgumentOutOfRangeException. int[] numbers = { 1, 2, 3, 4, 5 }; numbers.ElementAt(2); // 3 numbers.ElementAt(10); // throws ArgumentOutOfRangeException ElementAtOrDefault will return the item...

C# Language • LINQ Queries

Linq Quantifiers

Quantifier operations return a Boolean value if some or all of the elements in a sequence satisfy a condition. In this article, we will see some common LINQ to Objects scenarios where we can use these operators. There are 3 Quantifiers operations that can be used in LINQ: All – used to determine w...

C# Language • LINQ Queries

Using IntStream to iterate over indexes

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...

Java Language • Streams

Viewing the refcount of an object

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

Python Language • Garbage Collection

Create and use a GnuPG key quickly

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...

GNU/Linux • GnuPG (GPG)

Simple data bounded selection

var myData = [ { name: "test1", value: "ok" }, { name: "test2", value: "nok" } ] // We have to select elements (here div.samples) // and assign data. The second parameter of data() is really important, // it will determine the "key" t...

d3.js • Selections

Concatenation Operations

Concatenation refers to the operation of appending one sequence to another. Concat Concatenates two sequences to form one sequence. Method Syntax // Concat var numbers1 = new int[] { 1, 2, 3 }; var numbers2 = new int[] { 4, 5, 6 }; var numbers = numbers1.Concat(numbers2); // number...

linq • Standard Query Operators

Filtering Operations

Filtering refers to the operations of restricting the result set to contain only those elements that satisfy a specified condition. Where Selects values that are based on a predicate function. Method Syntax // Where var numbers = new int[] { 1, 2, 3, 4, 5, 6, 7, 8 }; var evens = number...

linq • Standard Query Operators

Join Operations

A join of two data sources is the association of objects in one data source with objects that share a common attribute in another data source. Join Joins two sequences based on key selector functions and extracts pairs of values. Method Syntax // Join class Customer { public int Id ...

linq • Standard Query Operators

Projection Operations

Projection refers to the operations of transforming an object into a new form. Select Projects values that are based on a transform function. Method Syntax // Select var numbers = new int[] { 1, 2, 3, 4, 5 }; var strings = numbers.Select(n => n.ToString()); // strings = { "1...

linq • Standard Query Operators