Tutorial by Examples: er

When PyInstaller is used without any options to bundle myscript.py , the default output is a single folder (named myscript) containing an executable named myscript (myscript.exe in windows) along with all the necessary dependencies. The app can be distributed by compressing the folder into a zip fi...

Header fields (usually just called ‘headers’) may be added to an HTTP request to provide additional information with the request. A header has semantics similar to parameters passed to a method in any programming language that supports such things. A request with Host, User-Agent and Referer header...

There are several good examples of using lambdas as a FunctionalInterface in simple scenarios. A fairly common use case that can be improved by lambdas is what is called the Execute-Around pattern. In this pattern, you have a set of standard setup/teardown code that is needed for multiple scenarios ...

This example uses a push button (tact switch) attached to digital pin 2 and GND, using an internal pull-up resistor so pin 2 is HIGH when the button is not pressed. const int LED_PIN = 13; const int INTERRUPT_PIN = 2; volatile bool ledState = LOW; void setup() { pinMode(LED_PIN, OUTPUT); ...

When to use Virtually all WPF controls make heavy use of dependency properties. A dependency property allows for the use of many WPF features that are not possible with standard CLR properties alone, including but not limited to support for styles, animations, data binding, value inheritance, and c...

When to use An attached property is a dependency property that can be applied to any DependencyObject to enhance the behavior of various controls or services that are aware of the property's existence. Some use cases for attached properties include: Having a parent element iterate through its c...

When to use A read-only dependency property is similar to a normal dependency property, but it is structured to not allow having its value set from outside the control. This works well if you have a property that is purely informational for consumers, e.g. IsMouseOver or IsKeyboardFocusWithin. How...

Generic parameters can also be bound to more than one type using the T extends Type1 & Type2 & ... syntax. Let's say you want to create a class whose Generic type should implement both Flushable and Closeable, you can write class ExampleClass<T extends Flushable & Closeable> { }...

The Common Lisp Quick Reference is a document which can be printed and bound as a booklet in various layouts to have a printed quick reference for Common Lisp.

To make a class a subclass of another class, use parent pragma: package Point; use strict; ... 1; package Point2D; use strict; use parent qw(Point); ... 1; package Point3D; use strict; use parent qw(Point); ... 1; Perl allows for multiple inheritance: package Point2D; use stri...

To filter a selection you can use the .filter() method. The method is called on a selection and returns a new selection. If the filter matches an element then it is added to the returned selection, otherwise it is ignored. If no element is matched then an empty selection is returned. The HTML Thi...

Most developers encounter backpressure when their application fails with MissingBackpressureException and the exception usually points to the observeOn operator. The actual cause is usually the non-backpressured use of PublishSubject, timer() or interval() or custom operators created via create(). ...

public static class ArrayHelpers { public static bool Contains<T>(this T[] array, T[] candidate) { if (IsEmptyLocate(array, candidate)) return false; if (candidate.Length > array.Length) return false; for (int a = 0; a <...

redis-cli is the Redis command line interface program that allows to send commands to Redis and read the replies sent by the server, directly from the terminal. Basic command line usage is below: Access to redis: $ redis-cli 127.0.0.1:6379> Access to redis with authentication: $ redis-cli ...

The dir() function can be used to get a list of the members of a class: dir(Class) For example: >>> dir(list) ['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__...

If efficiency is important, a fast way to iterate over pixels in a cv::Mat object is to use its ptr<T>(int r) method to obtain a pointer to the beginning of row r (0-based index). According to the matrix type, the pointer will have a different template. For CV_8UC1: uchar* ptr = image.ptr&...

ISO/ANSI SQL: SELECT Id, Col1 FROM TableName ORDER BY Id OFFSET 20 ROWS MySQL: SELECT * FROM TableName LIMIT 20, 42424242424242; -- skips 20 for take use very large number that is more than rows in table Oracle: SELECT Id, Col1 FROM (SELECT Id, Col1, row_num...

ISO/ANSI SQL: SELECT Id, Col1 FROM TableName ORDER BY Id OFFSET 20 ROWS FETCH NEXT 20 ROWS ONLY; MySQL: SELECT * FROM TableName LIMIT 20, 20; -- offset, limit Oracle; SQL Server: SELECT Id, Col1 FROM (SELECT Id, Col1, row_number() over (order by Id) RowNumbe...

<?php /** * Panel: WPCustomize * * Basic Customizer panel with basic controls. * * @since 1.0.0 * @package WPC */ // Exit if accessed directly. if ( ! defined( 'ABSPATH' ) ) { exit; } // Customize function. if ( ! function_exists( 'wpc_panel_wpcustomize' ) ) { ...

Panels can have sections, sections can have settings, and settings can have controls. Settings are saved in the database, while the controls for particular settings are only used to display their corresponding setting to the user. This code creates a basic section in the panel from above. Inside a...