rgchris

Iterators, Part I

In this article, I will introduce iterators and discuss how they offer an intuitive interface for addressing a diverse set of programming problems. Specifically, I'll explore the potential application of iterators in Rebol, highlighting how they complement Rebol's elegant and expressive approach to problem-solving.

What are Iterators?

Iterators are mechanisms used to traverse complex data structures without exposing their internal composition. They provide a standard interface for accessing the component parts of those structures sequentially, significantly simplifying the code built around them. Iterators typically share the following characteristics:

• Encapsulation: They encapsulate the domain logic of a given data structure, meaning you do not need to learn that structure to use it.
• Sequential Access: Each call presents the next logical component from that domain.

gurzgri

Red [
	title:  'mutator-object
	author: "Christian Ensel"
	usage:  [
		>> do %../mutator-object.red
		>> circle: mutator-object [
			#set area: does [if number? new [set-quiet in self 'radius square-root divide new pi]]
			#get area: does [multiply pi power radius 2]
			radius: 10
		]

luce80

Red []
;%numeric-spinner.red
;%area-plus.red
;%splitter.red
;%scrollable-panel.red
;%%multi-text-list.red
;%area-rt.red
;%spinner-panel.red
;%tipped-button.red

Oldes

Red [
  Title:   "HTML entities"
  Purpose: "To decode HTML entities in a text"
  Author:  "Oldes"
  Date:    12-May-2020
  Version: 1.0.2
  License: MIT
  Usage: [
    "Test: ♠ & ¢ <a> and Δδ ¾" =
    decode-html-entities {Test: &spades; & &#162; &lt;a&gt;&#32;and &Delta;&delta; &frac34;}

jemmanuel

This is based on a neat little post that I saw on Simon Frankau‘s blog that I thought I’d provide a few more details on, as well as bringing it to a wider audience. Some higher-level data structures in object-oriented programming languages have dynamic memory allocation. This is used to create objects (usually things that behave like lists) that can grow and shrink as the program executes. When initializing a regular array in C or Java, you have to specify the size of the array on creation, for example with

int myArray[] = new int[10];

rebolek

Rebol [
    Title: "Build"
    Author: ["Ladislav Mecir" "Brian Hawley"]
    File: %build.r
    Date: 2-May-2006/13:36:38+2:00
    History: [
        7/apr/2003/19:02 {using INSERT and ONLY keywords}
        30/Oct/2004/12:55 {intermediate version - alpha}
        31/Oct/2004/9:49 {intermediate - word - insert/only, :word - insert}
        4/Nov/2004/6:55 {word - insert and evaluate, :word - insert/only}

zeux

uint32_t murmur2(uint32_t h)
{
	h ^= h >> 13;
	h *= 0x5bd1e995;
	h ^= h >> 15;

	return h;
}

uint32_t murmur3(uint32_t h)

meijeru

Red [
	Title: 		"Word finder"
	Purpose:	{Find occurrences of words in the source files
				 of the Red toolchain and display them}
	Author:		"Rudolf W. MEIJER"
	File:		%word-finder.red
	Needs:		'View
	Rights:		"Copyright (c) 2019 Rudolf W. MEIJER"
	History:	[
					[0.0 23-Jan-2019 {Start of project}]

luce80

Red [
	title: "Update red scripts collection list"
	file: %add-script.red
	author: "Marco Antoniazzi"
	license: "Do with this code whatever you want, giving credit to me is NOT required"
	email: [luce80 AT alice DOT it]
	date: 01-07-2018
	version: 1.0.1
	Purpose: "Help update red scripts collection list"
	Needs: 'View

DideC

Red [
	Purpose: "Animation system for VID"
	Needs: 'View

	Notes: {
		Simplyfied Ease in/out formulas : http://gizma.com/easing/#l
		See at the end of page source for javascripts formulas (included elastic) : http://easings.net/en
	}
]