Keeping the PHP and the HTML apart

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Your Web application includes both presentation and logic, and that logic is further divided into business and display logic. How are you going to manage these various layers? How about keeping each of the logically separate areas in a separate file so that the look and feel can be maintained quite separate from the operations?

Here's a sample application written using this form of separation:

INDEX.PHP4 - THE TOP LAYER

<?
# Separating display, business logic and helpers
include "business.inc";
include "helpers.inc";
include "display.inc";
?>

DISPLAY.INC - THE PRESENTATION LAYER

<html>
<head><title><? title(); ?></title></head>
<body bgcolor=#CCCCFF><h1>Separating the logic</h1>
This is a demonstration of the separation of the "business logic"
from the main code on a PHP page. It's all transparent to the visitor
to your web site, but the page at the actual location called up is simply
a few includes and the real work is is in those:<ul><li>Business Logic
<li>Display Helper logic<li>Display template</ul>
<center><i>Using PHP as it's really intended ;-)</i></center><br><br>

<? result() ; ?>
<br><br>
<? question() ; ?> ...<p>
<form><table>
<tr><td>Let's have you enter an age:</td><td><? input_box("age",4); ?></td></tr>
<tr><td>and a gender</td><td><? input_radio("gender","Male|Female"); ?></td></tr>
<tr><td> and ... </td><td><input type=submit></td></tr>
</table>
</form><br><br>
<? copyright() ; ?>
</body>
</html>

HELPERS.INC - THE HELPERS LAYER

<?
function title() {
        global $title;
        echo $title;
        }
function question() {
        global $formheader;
        echo $formheader;
        }
function copyright() {
        echo "Copyright, Well House Consultants, ".date("Y");
        }
function result () {
        global $result;
        echo "** <u><b>$result</b></u> ** ";
        }
function input_radio($name,$options) {
        foreach (explode("|",$options) as $option) {
                echo "<input type=radio name=$name value=$option> $option<br>";
                }
        }
function input_box($name, $size) {
        echo "<input name=$name size=$size>";
        }
?>

BUSINESS.INC - THE BUSINESS LOGIC LEVEL

<?
$resolved = ($_GET[age] != "");

if ($_GET[age] > 19) {
        $describe = "Adult";
        if ($_GET[gender] == "Male") $describe = "Gentleman";
        if ($_GET[gender] == "Female") $describe = "Lady";
} elseif ($_GET[age] > 12) {
        $describe = "Teenager";
        if ($_GET[gender] == "Male") $describe = "Young Gentleman";
        if ($_GET[gender] == "Female") $describe = "Young Lady";
} elseif ($_GET[age] > 1) {
        $describe = "Child";
        if ($_GET[gender] == "Male") $describe = "Boy";
        if ($_GET[gender] == "Female") $describe = "Girl";
} else {
        $describe = "Baby";
}

if ($resolved) {
        $title = "About our person ....";
        $formheader = "Please enter details for another person";
        $result = "A $_GET[age] year old $_GET[gender] would be described as a '$describe'";
} else {
        $title = "A Welcome page";
        $formheader = "Please enter some information about a person";
        $result = "Your results will appear here";
        }

?>