Tutorial by Examples: p

The loop macro has two forms: the "simple" form and the "extended" form. The extended form is covered in another documentation topic, but the simple loop is useful for very basic loop. The simple loop form takes a number of forms and repeats them until the loop is exited using ...

The name Smalltalk usually refers to ANSI Smalltalk or Smalltalk 80 (of which the first is based on). While most implementations are close to the standard, they vary in different aspects (usually referred to as dialects). Each implementation has it's own method of installation. Well known FOSS imp...

Care must be taken when initializing variables of type float to literal values or comparing them with literal values, because regular floating point literals like 0.1 are of type double. This may lead to surprises: #include <stdio.h> int main() { float n; n = 0.1; if (n > ...

Description This is a self-contained running example including/showcasing: minimum dependencies needed, Java Configuration, Bean declaration by annotation and Java Configuration, Dependency Injection by Constructor and by Property, and Pre/Post hooks. Dependencies These dependencies are needed in...

A problem: Canvas only remembers pixels, not shapes or images This is an image of a circular beach ball, and of course, you can't drag the ball around the image. It may surprise you that just like an image, if you draw a circle on a Canvas you cannot drag that circle around the canvas. That's be...

Most Canvas drawings are either rectangular (rectangles, images, text-blocks) or circular (circles). Circles & rectangles have mathematical tests to check if the mouse is inside them. This makes testing circles and rectangles easy, quick and efficient. You can "hit-test" hundreds of c...

Here is an example of an IntentService that pretends to load images in the background. All you need to do to implement an IntentService is to provide a constructor that calls the super(String) constructor, and you need to implement the onHandleIntent(Intent) method. public class ImageLoaderIntentSe...

The exposition pipe operator, %$%, exposes the column names as R symbols within the left-hand side object to the right-hand side expression. This operator is handy when piping into functions that do not have a data argument (unlike, say, lm) and that don't take a data.frame and column names as arg...

Open Script Editor. 2.12.4 With Mac OS X Leopard and earlier, and OS X Yosemite and later, Script Editor is located at /Applications/Utilities/Script Editor.app 2.12.4 Between Mac OS X Snow Leopard and OS X Mavericks inclusive, Script Editor is AppleScript Editor. /Applications/Utiliti...

Composing multiple functions into one is a functional programming common practice; composition makes a pipeline through which our data will transit and get modified simply working on the function-composition (just like snapping pieces of a track together)... you start out with some single responsi...

Python's built-in crypto functionality is currently limited to hashing. Encryption requires a third-party module like pycrypto. For example, it provides the AES algorithm which is considered state of the art for symmetric encryption. The following code will encrypt a given message using a passphrase...

c++17 C++17 introduces int std::uncaught_exceptions() (to replace the limited bool std::uncaught_exception()) to know how many exceptions are currently uncaught. That allows for a class to determine if it is destroyed during a stack unwinding or not. #include <exception> #include <strin...

In VBA, this attribute is ignored. It was not ported over from VB6. In VB6, it creates a Default Global Instance of the class (a "shortcut") so that class members can be accessed without using the class name. For example, DateTime (as in DateTime.Now) is actually part of the VBA.Conversio...

Creates a Global Default Instance of a class. The default instance is accessed via the name of the class. Declaration VERSION 1.0 CLASS BEGIN MultiUse = -1 'True END Attribute VB_Name = "Class1" Attribute VB_GlobalNameSpace = False Attribute VB_Creatable = False Attribute VB_Pr...

Controls the instancing characteristics of a class. Attribute VB_Exposed = False Makes the class Private. It cannot be accessed outside of the current project. Attribute VB_Exposed = True Exposes the class Publicly, outside of the project. However, since VB_Createable is ignored in VBA, inst...

Adds a text description to a class or module member that becomes visible in the Object Explorer. Ideally, all public members of a public interface / API should have a description. Public Function GiveMeATwo() As Integer Attribute GiveMeATwo.VB_Description = "Returns a two!" ...

Transcrypt is a tool to precompile a fairly extensive subset of Python into compact, readable Javascript. It has the following characteristics: Allows for classical OO programming with multiple inheritance using pure Python syntax, parsed by CPython’s native parser Seamless integration with the ...

Once shadowing is turned on, every new drawing to the canvas will be shadowed. Turn off further shadowing by setting context.shadowColor to a transparent color. // start shadowing context.shadowColor='black'; ... render some shadowed drawings ... // turn off shadowing. context.shadowColor=...

Warning! Apply shadows sparingly! Applying shadowing is expensive and is multiplicatively expensive if you apply shadowing inside an animation loop. Instead, cache a shadowed version of your image (or other drawing): At the start of your app, create a shadowed version of your image in a secon...

The traditional use of shadowing is to give 2-dimensional drawings the illusion of 3D depth. This example shows the same "button" with and without shadowing var canvas=document.createElement("canvas"); var ctx=canvas.getContext("2d"); document.body.appendChild(can...