Tutorial by Examples: en

If-statements can be expressions: val str = if (condition) "Condition met!" else "Condition not met!" Note that the else-branch is not optional if the if-statement is used as an expression. This can also been done with a multi-line variant with curly brackets and multiple el...

The when-statement is an alternative to an if-statement with multiple else-if-branches: when { str.length == 0 -> print("The string is empty!") str.length > 5 -> print("The string is short!") else -> print("The string is long!") ...

When given an argument, the when-statement matches the argument against the branches in sequence. The matching is done using the == operator which performs null checks and compares the operands using the equals function. The first matching one will be executed. when (x) { "English" -...

Like if, when can also be used as an expression: val greeting = when (x) { "English" -> "How are you?" "German" -> "Wie geht es dir?" else -> "I don't know that language yet :(" } print(greeting) To be used as an express...

To get the next element you can use the .next() method. <ul> <li>Mark</li> <li class="anna">Anna</li> <li>Paul</li> </ul> If you are standing on the "Anna" element and you want to get the next element, "Paul...

public class Singleton { private static class InstanceHolder { static final Singleton INSTANCE = new Singleton(); } public static Singleton getInstance() { return InstanceHolder.INSTANCE; } private Singleton() {} } This initializes the INSTANCE vari...

Getting all the information of current user in wordpress using the predefined function wp_get_current_user(); <?php $current_user = wp_get_current_user(); echo "Username :".$current_user->user_login; echo "Username :".$current_user-&g...

function social_profiles( $contactmethods ) { $contactmethods['facebook_profile'] = 'Facebook Profile URL'; $contactmethods['twitter_profile'] = 'Twitter Profile URL'; $contactmethods['google_profile'] = 'Google Profile URL'; $contactmethods['linkedin_profile'] = 'Li...

A Stream of items that are in turn streamable can be flattened into a single continuous Stream: Array of List of Items can be converted into a single List. List<String> list1 = Arrays.asList("one", "two"); List<String> list2 = Arrays.asList("three&quot...

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. ...

It is sometimes useful to verify that your work on Developer edition hasn't introduced a dependency on any features restricted to Enterprise edition. You can do this using the sys.dm_db_persisted_sku_features system view, like so: SELECT * FROM sys.dm_db_persisted_sku_features Against the datab...

You can iterate on the object returned by groupby(). The iterator contains (Category, DataFrame) tuples. # Same example data as in the previous example. import numpy as np import pandas as pd np.random.seed(0) df = pd.DataFrame({'Age': np.random.randint(20, 70, 100), 'Sex':...

Consider the utility class pattern: a class with only static methods and no fields. It's recommended to prevent instantiation of such classes by adding a private a constructor. This live template example makes it easy to add a private constructor to an existing class, using the name of the enclos...

Maps and keyword lists have different application. For instance, a map cannot have two keys with the same value and it's not ordered. Conversely, a Keyword list can be a little bit hard to use in pattern matching in some cases. Here's a few use cases for maps vs keyword lists. Use keyword lists wh...

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...

You can generate a rails migration file from the terminal using the following command: rails generate migration NAME [field[:type][:index] field[:type][:index]] [options] For a list of all the options supported by the command, you could run the command without any arguments as in rails generate ...

Django comes with a number of builtin management commands, using python manage.py [command] or, when manage.py has +x (executable) rights simply ./manage.py [command] . The following are some of the most frequently used: Get a list of all available commands ./manage.py help Run your Django ser...

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')...

Some of the additional attributes are parsed by the npm website like repository, bugs or homepage and shown in the infobox for this packages { "main": "server.js", "repository" : { "type": "git", "url": "git+https:/...