Tutorial by Examples: od

Some metamethods don't have to be functions. To most important example for this is the __index metamethod. It can also be a table, which is then used as lookup. This is quite commonly used in the creation of classes in lua. Here, a table (often the metatable itself) is used to hold all the operation...

5.2 Objects in lua are garbage collected. Sometimes, you need to free some resource, want to print a message or do something else when an object is destroyed (collected). For this, you can use the __gc metamethod, which gets called with the object as argument when the object is destroyed. You could...

There are many more metamethods, some of them are arithmetic (e.g. addition, subtraction, multiplication), there are bitwise operations (and, or, xor, shift), comparison (<, >) and also basic type operations like == and # (equality and length). Lets build a class which supports many of these o...

Ionic Framework A Cross-platform mobile application development framework using Angular JS and Front End web technologies. Official website: http://ionicframework.com/ Documentation: http://ionicframework.com/docs/ Installation and Setup Installation Ionic required NPM(Node Package Manager) an...

The Windows API documentation for functions taking one or more string as argument will usually look like this: BOOL WINAPI CopyFile( _In_ LPCTSTR lpExistingFileName, _In_ LPCTSTR lpNewFileName, _In_ BOOL bFailIfExists ); The datatype for the two string parameters is made of several ...

really_neat.info name = Really Neat Module description = Provides a really neat page for your site core = 7.x really_neat.module <?php /** * @file * Hook implementation and shared functions for the Really Neat Module. */ /** * Implements hook_menu(). */ function really_nea...

git blame <file> will show the file with each line annotated with the commit that last modified it.

While RODBC is restricted to Windows computers with compatible architecture between R and any target RDMS, one of its key flexibilities is to work with Excel files as if they were SQL databases. require(RODBC) con = odbcConnectExcel("myfile.xlsx") # open a connection to the Excel file s...

First need to create a final static logger object: final static Logger logger = Logger.getLogger(classname.class); Then, call logging methods: //logs an error message logger.info("Information about some param: " + parameter); // Note that this line could throw a NullPointerException!...

Sometimes you need to keep a linear (non-branching) history of your code commits. If you are working on a branch for a while, this can be tricky if you have to do a regular git pull since that will record a merge with upstream. [alias] up = pull --rebase This will update with your upstream so...

#!/bin/bash NO_SNAPSHOTS="No snapshots have been taken yet" SNAPSHOT_OUTPUT=$(vagrant snapshot list | grep "${NO_SNAPSHOTS}") if [ -z "${SNAPSHOT_OUTPUT}" ]; then echo "Found some snapshots, going to remove them" for SNAPSHOT in $(vagrant snap...

Intervals are simplest way of recording timespans in lubridate. An interval is a span of time that occurs between two specific instants. # create interval by substracting two instants today_start <- ymd_hms("2016-07-22 12-00-00", tz="IST") today_start ## [1] "2016-07-...

Unlike durations, periods can be used to accurately model clock times without knowing when events such as leap seconds, leap days, and DST changes occur. start_2012 <- ymd_hms("2012-01-01 12:00:00") ## [1] "2012-01-01 12:00:00 UTC" # period() considers leap year calculati...

String hubUrl = "http://localhost:4444/wd/hub" DesiredCapabilities capability = DesiredCapabilities.firefox(); //or which browser you want RemoteWebDriver driver = new RemoteWebDriver(hubUrl, capability);

Creating a hub A quick configuration for a hub and node setup in selenium grid. For more information see: Grid 2 docs Requirements To set up a grid hub you need the flowing: Selenium-server-standalone-.jar Creating the hub To Create a Hub you need to run the selenium server. Download Se...

Extension methods are useful for adding functionality to enumerations. One common use is to implement a conversion method. public enum YesNo { Yes, No, } public static class EnumExtentions { public static bool ToBool(this YesNo yn) { return yn == YesNo.Yes; ...

Modal pages can created in three ways: From NavigationPage object for full screen pages For Alerts and Notifications For ActionSheets that are pop-ups menus Full screen modals ... // to open await Navigation.PushModalAsync(new ModalPage()); // to close await Navigation.PopModalAsync(); ...

After you've created and registered your platform-specific classes you can start hooking them up to your shared code. The following page contains a button that triggers the text-to-speech functionality using a pre-defined sentence. It uses DependencyService to retrieve a platform-specific implementa...

A 2-tuple or a 3-tuple represent a group of related items. (Points in 2D space, RGB values of a color, etc.) A 1-tuple is not very useful since it could easily be replaced with a single int. A 0-tuple seems even more useless since it contains absolutely nothing. Yet it has properties that make it v...

All you need is a variable of type IHostingEnvironment: get environment name: env.EnvironmentName for predefined Development, Staging, Production environments the best way is to use extension methods from HostingEnvironmentExtensions class env.IsDevelopment() env.IsStaging() ...