如何避免两个同名的班级？

In my php file i am doing it this way

pagecontroller.php

include_once(RUDRA."/controller/AbstractTemplateController.php");
if (file_exists(get_include_path() . CONTROLLER_PATH . "/TemplateController.php" )) {
    include_once (CONTROLLER_PATH . "/TemplateController.php");
} else {
    include_once (RUDRA . "/controller/TemplateController.php");
}

in TemplateController.php a class named 'TemplateController extends AbstractTemplateController' is defined, if a developer has already defined a class TemplateController which also extends AbstractTemplateController then it will use that otherwise it will fallback to default definition.

then in other files i will simply use something like this

include_once("pagecontroller.php")
$c = new TemplateController();

is there any better way to do this? since I am including two files AbstractTemplateController.php & TemplateController.php in both cases, I cpuld have written both class definitions in same file which would have saved one include(if there is no custom TemplateController.php)?

I tried writing AbstractTemplateController & TemplateController in one single file but if then developer has defined his own TemplateController it creates two classes with same name situation.

pupose is to have atleast one definition to be there, if customDefinition does not exists then only use default one. and this code is to be abstract.

in the beginning if CustomClass exists (in a specific folder) then that the definition to be used, else use default one (which is nothing but simply extends AbstractOne)

CONTROLLER_PATH . "/TemplateController.php"

class TemplateController extends AbstractTemplateController {
        /* over-ridden method of AbstractTemplateController
        */
    public function invoke($abc,$def){
     echo $abc . "   " .$def;
    }
}

RUDRA . "/controller/TemplateController.php"

class TemplateController extends AbstractTemplateController {
// nothing at all this is simply to make sure TemplateController class is available
// for others to use.
}

Use namespaces and convention.

E.g. you could check if there's a TemplateController-class present that extends the AbstractTemplateController that's different from your namespace (As your implementation will be specific for your namespace), if there isn't ; fall back to your implementation of the TemplateController.

http://php.net/manual/en/language.namespaces.php

php provides a function for not letting you load/write a class more then once.

bool class_exists ( string $class_name );

example is :

<?php
function __autoload($class)
{
    include($crigger_error("Unable to load class: $class", E_USER_WARNING);
    }
}

if (class_exists('MyClass')) {
    $myclass = new MyClass();
}lass . '.php');

    // Check to see whether the include declared the class
    if (!class_exists($class, false)) {
        trigger_error("Unable to load class: $class", E_USER_WARNING);
    }
}

if (class_exists('MyClass')) {
    $myclass = new MyClass();
}

?>

in above example autoload is used, you could do it without autoload this way :

<?php
// Check that the class exists before trying to use it
if (class_exists('MyClass')) {
    $myclass = new MyClass();
}

?>

still i am saying you better get habit of using namespaces. they are awesome and work every where.