PHP 5/MySQL Programming- P52 pptx

The phrase Basic Super Page is the string that initializes the SuperHTML object.. The buildBottom method is even easier than buildTop, because it simply adds some boilerplate page-ending

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It’s not that amazing that the function can generate all that HTML code; the code

is fairly predictable What’s neat is the way the SuperHTMLobject knew what its

title and headline should be The phrase Basic Super Page is the string that

initializes the SuperHTML object The buildBottom() method is even easier than

buildTop(), because it simply adds some boilerplate page-ending code:

</body>

</html>

Writing Out the Page

The buildTop()and buildBottom()directives feel a lot like function calls, because

they are very similar to the functions you’ve already created and used many

times However, these functions are designed to work within the context of a

par-ticular object A function attached to an object is referred to as a method of the

object A cowobject might have moo()and giveMilk() methods

The syntax for referring to methods in PHP is with the arrow syntax (->) There isn’t one key to indicate this operator It is the combination of the dash and the greater-than symbol.

Note that neither buildTop() nor buildBottom() actually write any code to the

screen Instead, they prepare the page as a long string property inside the object

SuperHTMLhas a method called getPage()that returns the actual HTML code for

the page The programmer can then save the code to a file, print it out, or

what-ever In this case, the following line simply prints out the results of the getPage()

method:

print $s->getPage();

Working with the Title Property

It’s possible to designate a title when you create a SuperHTMLobject, but what if

you want to change the title later? Objects can store code in methods, and they

can also store data in properties A property is like a variable attached to a

par-ticular object The SuperHTMLobject has a title property The cowobject might have

a breedproperty and an ageproperty The Properties.php page featured in Figure

7.2 illustrates this feature

The Property.php program begins exactly like the Basic Super page you saw

ear-lier I even created the $svariable with the same initial value (Basic Super Page)

H I N T

When I created the SuperHTMLobject, the title property was automatically set to Basic Super Page It’s possible to directly change the title, like this:

$s ->title = “new title”;

As you see when you look at the SuperHTMLcode itself, this approach can cause some problems It’s generally better to use special methods to get information to and from properties Take a look at the following code for Property.php and you’ll see a better way to change a property value

<?

include “SuperHTMLDef.php”;

$s = new SuperHTML(“Basic Super Page”);

$s->setTitle(“I changed this”);

$s->buildTop();

print “The title is now “ $s->getTitle();

$s->buildBottom();

print $s->getPage();

?>

The $s->setTitle() method allows me to add a new value to a property The

$s->getTitle()method gets a value from a property These special methods are usually called access methods because they allow access to properties I’ll explain more about access methods later in this chapter when you start building your own object

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FIGURE 7.2

I created this page

with one title

and then changed

the title.

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Adding Text and Tags with SuperHTML

The SuperHTML object makes it easy to build a basic HTML framework, but you

always need other kinds of tags SuperHTMLhas some general methods for adding

various kinds of tags and text to a document Figure 7.3 illustrates a page using

these features

One of the primary features of SuperHTMLis the way it separates the creation of a

Web page from its display You want to be able to easily generate a page and then

display it onscreen, write it to a file, or do whatever else you want with it For

that reason, you won’t simply print things out Instead, you’ll keep adding stuff

to the SuperHTMLobject and then print the whole thing out when you’re done

That means you need some mechanism for adding things to the page The SuperHTML

object contains more than 25 methods for adding various kinds of objects to the

document (Don’t panic Most of them are really very simple.) Two methods in

par-ticular are extremely useful Look at the code for AddText.phpand see what I mean

FIGURE 7.3

This page includes

some text and

HTML tags.

I N THE R EAL W ORLD

If you’ve programmed in languages like Visual Basic, C#, or Java, you might

argue that you have directly accessed properties without using these access

methods The truth is, access methods in these languages are usually behind

the scenes When you assign a value to an object property, the appropriate

access method is automatically implemented

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<?

include “SuperHTMLDef.php”;

$s = new SuperHTML(“Adding Text and Tags”);

$s->buildTop();

$s->addText(“This is ordinary text added to the document”);

$s->addText(“<div>You can also add HTML code <hr> like the HR above</div>”);

$s->h3(“Use h1-h6 methods to add headings”);

$s->tag(“i”, “this line is italicized”);

$s->buildBottom();

print $s->getPage();

?>

The addText() method expects a string as its only parameter It then adds that text to the document in memory As you can see, the text can even contain HTML data You can also pass multi-line strings or text with interpolated variables The addText()method is really the only method you need in order to build the page in memory However, the point of the SuperHTMLobject is to make page devel-opment faster and easier I actually use the addText()method when I need to add actual text to a page or when I need a tag I haven’t yet implemented in SuperHTML Look at the following line:

$s->h3(“Use h1-h6 methods to add headings”);

This code accepts a string as a parameter, then surrounds the text with <h3></h3> tags and writes it to the document in memory Of course, there are similar methods for h1 through h6 You could expect similar methods for all the basic HTML tags

I didn’t create shortcuts for all the HTML tags, for two reasons One reason is once you see the mechanism for creating a new tag method, you can modify SuperHTML very easily to have methods for all your favorite tags The other reason I didn’t make shortcuts for all the tags is the very special method described in the fol-lowing line:

$s->tag(“i”, “this line is italicized”);

The tag()method is a workhorse It expects two parameters The first is the tag you wish to implement (without the angle braces) In this case I want to italicize,

so I’m implementing the itag The second parameter is the text you want sent

to the document After this function is completed, the document has the following

text added to the end:

<i>this line is italicized</i>

If you look at the HTML source code for AddText.php, you see that’s exactly what

happened

The great thing about the tag()method is its flexibility It can surround any text

with any tag

Creating Lists the SuperHTML Way

Even if you only use the addText()and tag()methods, you can create some really

nice, flexible Web pages However, this object’s real power comes with some

spe-cialized methods that solve specific display problems When you think about it,

a lot of PHP constructs have natural companions in the HTML world For

exam-ple, if you have an array of data in PHP, you frequently want to display it in some

form of HTML list Figure 7.4 demonstrates a page with a number of lists, all

auto-matically generated from arrays

You’ve probably already written code to generate an HTML list from an array

Although it’s not difficult, it can be tedious It’d be great if you could just hand

off that functionality and not worry about it when you’ve got other problems to

solve The SuperHTML object has exactly that capability The code list.php

illus-trates a number of ways to do this

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FIGURE 7.4

These HTML lists

were created

automatically from

arrays.