[TYPO3-dev] Extend class in extension's creation

[Hraklis Karvasonis]

Hi.

I am creating a new extension from kickstarter that has a standard class 
file like class.myextension.php

i would like to extend this class in another class file, for example 
class.mynewclass.php, within the extension, but i receive some errors 
when doing that.

i cannot include the class.myextension.php in the new class.

when i write 
require_once(t3lib_extMgm::extPath('myextension').'class.myextension.php');
in the new class i receive an error that it cannot find this class.

What i am trying to do is to add a new insert query in the new class 
file like this:

$GLOBALS['TYPO3_DB']->exec_INSERTquery('myextension',$field_values);

which libraries do i have to include in the new class in order to do 
this? Because i tried to add several libraries there and i always 
receive the message that it cannot find this class.

i am also adding at the bottom of the new class file the following lines:

if (defined('TYPO3_MODE') && 
$TYPO3_CONF_VARS[TYPO3_MODE]['XCLASS']['ext/myextension/pi1/class.mynewclass.php']) 
{include_once($TYPO3_CONF_VARS[TYPO3_MODE]['XCLASS']['ext/myextension/pi1/class.mynewclass.php']);
}

Can you give me any help on how to do this?

Thanks.