Tutorial by Examples: v

In the most basic form, it is possible to select a single variable from a table by calling the object's get_var method passing in an SQL query. global $wpdb; $user = $wpdb->get_var( "SELECT ID FROM $wpdb->users WHERE user_email='[email protected]'" ); It is very important to note that...

A generator is a combination of two things - an Iterator and an Observer. Iterator An iterator is something when invoked returns an iterable. An iterable is something you can iterate upon. From ES6/ES2015 onwards, all collections (Array, Map, Set, WeakMap, WeakSet) conform to the Iterable contract...

function remove_contact_methods( $contactmethods ) { unset($contactmethods['facebook_profile']); unset($contactmethods['twitter_profile']); return $contactmethods; } add_filter( 'user_contactmethods', 'remove_contact_methods', 10, 1);

Package names Package names should be all lower case without underscores or other special characters. Package names begin with the reversed authority part of the web address of the company of the developer. This part can be followed a by project/program structure dependent package substructure. ...

The .split() method splits a string into an array of substrings. By default .split() will break the string into substrings on spaces (" "), which is equivalent to calling .split(" "). The parameter passed to .split() specifies the character, or the regular expression, to use for...

JavaScript does not technically support private members as a language feature. Privacy - described by Douglas Crockford - gets emulated instead via closures (preserved function scope) that will be generated each with every instantiation call of a constructor function. The Queue example demonstra...

import os import glob import pandas as pd def get_merged_csv(flist, **kwargs): return pd.concat([pd.read_csv(f, **kwargs) for f in flist], ignore_index=True) path = 'C:/Users/csvfiles' fmask = os.path.join(path, '*mask*.csv') df = get_merged_csv(glob.glob(fmask), index_col=None, use...

This example shows a simple image cropping function that takes an image and cropping coordinates and returns the cropped image. function cropImage(image, croppingCoords) { var cc = croppingCoords; var workCan = document.createElement("canvas"); // create a canvas workCan.wi...

C++11 In C++11, compilers are required to implicitly move from a local variable that is being returned. Moreover, most compilers can perform copy elision in many cases and elide the move altogether. As a result of this, returning large objects that can be moved cheaply no longer requires special ha...

Let's have a basic failing program: #include <iostream> void fail() { int *p1; int *p2(NULL); int *p3 = p1; if (p3) { std::cout << *p3 << std::endl; } } int main() { fail(); } Build it (add -g to include debug info): g++ -g -o m...

Let's say we need to add a button for each piece of loadedData array (for instance, each button should be a slider showing the data; for the sake of simplicity, we'll just alert a message). One may try something like this: for(var i = 0; i < loadedData.length; i++) jQuery("#container&q...

This example shows how to configure multiple environments with different Dependency Injection configuration and separate middlewares in one Startup class. Alongside of public void Configure(IApplicationBuilder app) and public void ConfigureServices(IServiceCollection services) methods one can use C...

Often times you will want to have events for your objects. function spanOver(d,i){ var span = d3.select(this); span.classed("spanOver",true); } function spanOut(d,i){ var span = d3.select(this); span.classed("spanOver", false); } var div = d3.select('#divID')...

In development, you may find that using require() on the same module multiple times always returns the same module, even if you have made changes to that file. This is because modules are cached the first time they are loaded, and any subsequent module loads will load from the cache. To get around ...

You can loop over any iterable by using the standard for-loop: val list = listOf("Hello", "World", "!") for(str in list) { print(str) } Lots of things in Kotlin are iterable, like number ranges: for(i in 0..9) { print(i) } If you need an index while...

Higher-order functions can be used to ensure that system resources are disposed, even when a treatment raises an exception. The pattern used by with_output_file allows a clean separation of concerns: the higher-order with_output_file functions takes care of managing the system resources bound to fi...

Observables are broadly categorised as Hot or Cold, depending on their emission behaviour. A Cold Observable is one which starts emitting upon request(subscription), whereas a Hot Observable is one that emits regardless of subscriptions. Cold Observable /* Demonstration of a Cold Observable */ Ob...

A collection of navigational elements (usually links) for navigating the document or related documents. <ul role="navigation"> <li><a href="/">Home</a></li> <li><a href="/about">About</a></li> <li>&lt...

In general, it is considered good practice to throw by value (rather than by pointer), but catch by (const) reference. try { // throw new std::runtime_error("Error!"); // Don't do this! // This creates an exception object // on the heap and would require you to catch the ...

Even when all your work is directed at a single worksheet, it's still a very good practice to explicitly specify the worksheet in your code. This habit makes it much easier to expand your code later, or to lift parts (or all) of a Sub or Function to be re-used someplace else. Many developers establi...