OOP in PHP, just learning, but confused.

peterv12 · Dec 5, 2009

I want to learn OOP, and I found an article online that shows some PHP OOP examples. When I copy them and attempt to run them, I get the following error:

Code:

[COLOR=red][b]Fatal error: Cannot access empty property in /Users/peterv/Sites/PROJECT3/index.php on line 13[/b][/color]

I have the following two scripts, the first one titled index.php:

Code:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>OOP Test Project</title>
    </head>
    <body>
        <?php
        include "Student.php";

        $a_student = new Student("John","Male");

        print $a_student->$Name;

        ?>
    </body>
</html>

The second script is:

Code:

<?php

class Student {
    var $Name;
    var $Gender;
    
/* Constructor */
function Student($studentName, $studentGender) {
    $this->Name=$studentName;
    $this->Gender=$studentGender;
}

}
?>

The way I understand it is the index.php script should call the Student.php class (second script) passing it two variables, and Student.php should print the values in a web page, but all I get is the error message. I'm new to OOP, so I may be totally off base by how this should be coded, I'm just going by the article I found on the web. Any help, or explanations will be greatly appreciated!

DonQuichote · Dec 6, 2009

Code:

print $a_student->[red]$[/red]Name;

This reads as: take the variable $Name, use its contents as a string and use this as the property name of the property to print.

Code:

print $a_student->Name;

Would work. Note that you are using PHP4 syntax, and PHP4 is already end-of-life. What's more, you use a variable within an object directly, thereby denying the object the responsibility for it. Object orientation is all about responsibility. So even for "just a variable" you would write a function that returns it. That function could just pass the variable, or even lazily initialize it. That choice is internal to the object and therefore encapsulated.

+++ Despite being wrong in every important aspect, that is a very good analogy +++
Hex (in Darwin's Watch)

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OOP in PHP, just learning, but confused.

peterv12

Technical User

DonQuichote

Programmer

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