Tutorial by Examples: s

In Smalltalk almost everything you do is sending messages to objects (referred as calling methods in other languages). There are three types of messages: Unary messages: #(1 2 3) size "This sends the #size message to the #(1 2 3) array. #size is a unary message, because it takes no argumen...

Classes and methods are usually defined in the Smalltalk IDE. Classes A class definition looks something like this in the browser: XMLTokenizer subclass: #XMLParser instanceVariableNames: '' classVariableNames: '' poolDictionaries: '' category: 'XML-Parser' This is actually...

You can create extension methods to improve usability for nested collections like a Dictionary with a List<T> value. Consider the following extension methods: public static class DictListExtensions { public static void Add<TKey, TValue, TCollection>(this Dictionary<TKey, TColl...

This works well for single level right click context menu. All you need to do is create a registry entry under Classes Root HKEY_CLASSES_ROOT for specific extension. If you want to create a entry for all types of files choose * else choose extension like .pdf etc. var regmenu = Registry.ClassesR...

When you need multi level menus, with multiple parameters SharpShell comes to rescue. https://github.com/dwmkerr/sharpshell has umpteen number of examples and it works perfect even for single level to multi level custom context menus. Key thing is to create class with attributes [ComVisible(true)]...

Usage of loops is an excellent way to keep the code DRY and avoid repetition. Unlike in Sass, there are no built-in @for or @each directive in Less for writing loops but it can still be written using recursive mixins. A recursive mixin is nothing but a mixin which keeps calling itself. There are fo...

private final Logger logger = Logger.getLogger(getClass().getCanonicalName()); WebView webView = new WebView(); webEngine = webView.getEngine(); webEngine.setOnAlert(event -> logger.warning(() -> "JS alert: " + event.getData()));

When using a WebView to display your own custom webpage and this webpage contains Javascript, it might be necessary to establish a two-way communication between the Java program and the Javascript in the web page. This example shows how to setup such a communication. The webpage shall display an i...

Problem Cross-Site Request Forgery or CSRF can force an end user to unknowingly generate malicious requests to a web server. This attack vector can be exploited in both POST and GET requests. Let's say for example the url endpoint /delete.php?accnt=12 deletes account as passed from accnt parameter ...

The display of elements in a list or grids is a very common pattern in mobile applications. The user sees a collection of items and can scroll through them. The collection of items can be a list, a grid or another structured representations of data. The RecyclerView widget is a more advanced and fl...

Installing TeamCity server Setting up and Running Additional Build Agents

You can concatenate strings separated by delimiter using the string_agg() function. If your individuals table is: NameAgeCountryAllie15USAAmanda14USAAlana20Russia You could write SELECT ... GROUP BY statement to get names from each country: SELECT string_agg(name, ', ') AS names, country FROM ...

Bash can easily create lists from alphanumeric characters. # list from a to z $ echo {a..z} a b c d e f g h i j k l m n o p q r s t u v w x y z # reverse from z to a $ echo {z..a} z y x w v u t s r q p o n m l k j i h g f e d c b a # digits $ echo {1..20} 1 2 3 4 5 6 7 8 9 10 11...

Sometimes it's useful to test private & protected methods as well as public ones. class Car { /** * @param mixed $argument * * @return mixed */ protected function drive($argument) { return $argument; } /** * @return bool *...

Selection with increasing scope This comes handy when you want to select a block to extract a variable / method etc, no need to do a precise bracket matching, just put the caret somewhere in the statement and keep doing this Windows: Ctrl + W OS X / macOS: Cmd + W Selection with decreasing scope...

The only major differences between this and a regular TCP connection are the private Key and the public certificate that you’ll have to set into an option object. How to Create a Key and Certificate The first step in this security process is the creation of a private Key. And what is this private ...

SolrJ comes as part of the Solr distribution since Solr 1.x. The latest Solr version can be downloaded here. From Solr-6.3.0 that is the latest version available, we need to get the following libraries and add them to our build path: /dist/apache-solr-solrj-.jar /dist/solrj-lib/ Once we're done,...

CREATE TABLE users (username text, email text); CREATE TABLE simple_users () INHERITS (users); CREATE TABLE users_with_password (password text) INHERITS (users); Our three tables look like this: users ColumnTypeusernametextemailtext simple_users ColumnTypeusernametextemailtext users_with_p...

Let's create two simple tables: CREATE TABLE users (username text, email text); CREATE TABLE simple_users () INHERITS (users); Adding columns ALTER TABLE simple_users ADD COLUMN password text; simple_users ColumnTypeusernametextemailtextpasswordtext Adding the same column to the parent ta...

With AspNetCore you can develop the application on any platform including Mac,Linux,Window and Docker. Installation and SetUp Install visual Studio Code from here Add C# extesnion Install dot net core sdk. You can install from here Now you have all the tools available. To develop the applic...