Class not found PHP OOP

问题

I can't get this to work.

<?php


        function __autoload($classname){
            include 'inc/classes/' . $classname . '.class.php';
        }



__autoload("queries")

$travel = new queries();
echo $travel->getPar("price");

?>

And this is the inc/classes/queries.class.php file.

<?

 class queries {

        function getPar($par, $table='travel', $type='select') {

            $result = $db->query("
             $type *
             FROM $table
             WHERE
             $par LIKE
            ");
            while ($row = $result->fetch_assoc()) {

                return "
                 $row[$par]
                ";
            }

    }
}

?>

It returns "Class 'queries' not found". What's wrong with it?

EDIT:

Fatal error: Cannot redeclare __autoload() (previously declared in /index.php:5) in /index.php on line 5

What the hell? I can't redeclare a function that is already declared in its own line, why?

回答1:

Instead of that dreadful abomination, you should learn how to utilize spl_autoload_register():

spl_autoload_register( function( $classname ){

    $filename = 'inc/classes/' . $classname . '.class.php';

    if ( !file_exists( $filename) ){
        throw new Exception("Could not load class '$classname'.". 
                            "File '$filename' was not found !");
    }

    require $filename;

});

And you should register the autoloader in your index.php or bootstrap.php file, and do it only once per loader (this ability lets you define multiple loaders, but that's used, when you have third party library, which has own autoloader .. like in case of SwiftMailer).

P.S. please learn to use prepared statements with MySQLi or PDO.

Update

Since you are just now learning OOP, here are few things, which you might find useful:

Lectures:

Advanced OO Patterns
Inheritance, Polymorphism, & Testing
Recognizing smelly code
Global State and Singletons
Don't Look For Things!

Books:

PHP Object-Oriented Solutions
Patterns of Enterprise Application Architecture

回答2:

Try so (without class autoload):

function __autoload($classname){
    include_once 'inc/classes/' . $classname . '.class.php';
}
$travel = new queries();

Also see this link

回答3:

remove this line from you code __autoload("queries"), you don't need to call autoloader it will be called by it self whenever it encounters any undeclared class and use require_once instead of include and debug if you paths are correct or not.

来源：https://stackoverflow.com/questions/11375225/class-not-found-php-oop

标签

php

oop

autoloader