Tutorial by Examples: an

from datetime import timedelta from django.utils import timezone from psycopg2.extras import DateTimeTZRange # To create a "period" object we will use psycopg2's DateTimeTZRange # which takes the two datetime bounds as arguments period_start = timezone.now() period_end = period_s...

Use defdelegate to define functions that delegate to functions of the same name defined in another module: defmodule Math do defdelegate pi, to: :math end iex> Math.pi 3.141592653589793

Inheritance the a fundamental mechanism of CSS by which the computed values of some properties of an element are applied to its' children. This is particularly useful when you want to set a global style to your elements rather than having to set said properties to each and every element in your mark...

Some properties are not automatically inherited from an element down to its' children. This is because those properties are typically desired to be unique to the element (or selection of elements) to which the property is applied to. Common such properties are margin, padding, background, display, e...

Simple item insertion can be done with Array.prototype.splice method: arr.splice(index, 0, item); More advanced variant with multiple arguments and chaining support: /* Syntax: array.insert(index, value1, value2, ..., valueN) */ Array.prototype.insert = function(index) { this.splice.a...

With the appropriate storage backend running a new titan graph can be initialised via: graph = TitanFactory.open("config.properties"); Wehere config.properties defines several configurations relevant to the storage backend. Titan provides some sample configs in its downloadable package...

// Uses Windows authentication. Replace the Trusted_Connection parameter with // User Id=...;Password=...; to use SQL Server authentication instead. You may // want to find the appropriate connection string for your server. string connectionString = @"Server=myServer\myInstance;Database=myDa...

To initialize react-native init MyAwesomeProject To initialize with a specific version of React Native react-native init --version="0.36.0" MyAwesomeProject To Run for Android cd MyAwesomeProject react-native run-android To Run for iOS cd MyAwesomeProject react-native run-io...

The <see> tag can be used to link to another class. It contains the cref member which should contain the name of the class that is to be referenced. Visual Studio will provide Intellsense when writing this tag and such references will be processed when renaming the referenced class, too. /// ...

The System.String class supports a number of methods to convert between uppercase and lowercase characters in a string. System.String.ToLowerInvariant is used to return a String object converted to lowercase. System.String.ToUpperInvariant is used to return a String object converted to upper...

There are two functions that can be used to obtain a readable representation of an object. repr(x) calls x.__repr__(): a representation of x. eval will usually convert the result of this function back to the original object. str(x) calls x.__str__(): a human-readable string that describes the obje...

There are two main approaches to creating a thread in Java. In essence, creating a thread is as easy as writing the code that will be executed in it. The two approaches differ in where you define that code. In Java, a thread is represented by an object - an instance of java.lang.Thread or its subcl...

Matching an email address within a string is a hard task, because the specification defining it, the RFC2822, is complex making it hard to implement as a regex. For more details why it is not a good idea to match an email with a regex, please refer to the antipattern example when not to use a ...

A simple example: CL-USER> (defun make-apply-twice (fun) "return a new function that applies twice the function`fun' to its argument" (lambda (x) (funcall fun (funcall fun x)))) MAKE-APPLY-TWICE CL-USER> (funcall (make-apply-twice #'1+) 3) 5 ...

NA is a logical type and a logical operator with an NA will return NA if the outcome is ambiguous. Below, NA OR TRUE evaluates to TRUE because at least one side evaluates to TRUE, however NA OR FALSE returns NA because we do not know whether NA would have been TRUE or FALSE NA | TRUE # [1] TRUE ...

$state.go is shorthand method to $state.transitionTo $state.go(toState [, toParams] [, options]) This method automatically sets your options to { location: true, inherit: true, relative: $state.$current, notify: true } (unless you override them) and allows you to transition with less code. Ex...

Constants in Go may be typed or untyped. For instance, given the following string literal: "bar" one might say that the type of the literal is string, however, this is not semantically correct. Instead, literals are Untyped string constants. It is a string (more correctly, its default ...

Sometimes you may want maintain versions of a git repository on machines that have no network connection. Bundles allow you to package git objects and references in a repository on one machine and import those into a repository on another. git tag 2016_07_24 git bundle create changes_between_tags...

Create new Jekyll Post To create a new Jekyll Post, create a new file on _posts directory with the format YYYY-MM-DD-title.MARKUP Replace MARKUP with the file extension for the language you want to use. This is usually Markdown(.md or .markdown) or HTML(.html). _posts/2017-01-01-hello-jekyll.m...

In some cases you might want to add an additional description to an enum value, for instance when the enum value itself is less readable than what you might want to display to the user. In such cases you can use the System.ComponentModel.DescriptionAttribute class. For example: public enum Possibl...