Time for action—Representing different types of articles

Now, imagine that the company you work for wants a blog with different types of articles— text-based articles and image-based articles. What they want is simple: a text-based article that is made of a String, and an image-based article that stores the URL of the image. All types of articles need to have a title.

At first, let's write the Article class. This one will define what all articles have. 

class Article
{
public var title : String;
}

Notice that we did not create a constructor for this class: an article has to be either text-based or image-based in this example, being able to construct an instance of the Article class would be nonsense.

We want text-based and image-based articles to be able to generate some HTML code, but each one will need to do it in its own way. To make it usable by a calling function, we will define an IHTMLGenerator interface, as follows: 

interface IHTMLGenerator
{
public function generateHTML() : String;
}
  1. Now let's write what a text-based article is:
    class TextArticle extends Article, implements IHTMLGenerator
{
public var text : String; public function new(text : String)
{
this.text = text;
}
public function generateHTML() : String
{
returnStringTools.htmlEscape(text);
}
}
  2. Now, let's define what an image-based article is:
    class ImageArticle extends Article, implements IHTMLGenerator
{
public var imageUrl : String; public function new(url : String)
{
this.imageUrl = url;
}
public function generateHTML() : String
{
return '<imgsrc="' + this.imageUrl + '" alt=' + this.title + '/>';
}
}
  3. Finally, in our Main class, we will add two methods: one that displays the title of an article and one that outputs its HTML code:
    class Main
{
public static function main()
{
var imgArt : ImageArticle;
imgArt = new ImageArticle
("http://www.someuninterestingblog.unexistingtld/someimage.png");
imgArt.title = "Some unexisting image";
var textArt : TextArticle;
textArt = new TextArticle("This is an interesting text");
textArt.title = "Some interesting article";
displayArticleTitle(imgArt);
outputHTMLCode(imgArt);
displayArticleTitle(textArt);
outputHTMLCode(textArt);
}
public static function displayArticleTitle(art : Article)
{
trace(art.title);
}
public static function outputHTMLCode (generator : IHTMLGenerator)
{
trace(generator.generateHTML());
}
}
  4. Now, you can compile and run your code! You should get the following output:
    Main.hx:20: Some unexisting image Main.hx:25: <img src="http://www.someuninterestingblog.unexistingtld/someimage.png"/> Main.hx:20: Some uninteresting article Main.hx:25: This is an uninteresting text
..................Content has been hidden....................

You can't read the all page of ebook, please click here login for view all page.
Reset
3.145.166.149