Does anybody know how can I locate the physical path of a class in Magento?
For example this class: Idev_OneStepCheckout_Block_Adminhtml_Sales_Order_View_Comment
Seems that it follows a pattern of folders - but its not always the case.
Can you give me an idea how to locate this class ?
Magento names classes the way Zend Framework does. Replace the undescore with a slash and get the name of the file and ad .php at the end. So in your case Idev_OneStepCheckout_Block_Adminhtml_Sales_Order_View_Comment should be located in the file Idev/OneStepCheckout/Block/Adminhtml/Sales/Order/View/Comment.php. This path is relative to a codepool. Magento has 3 such codepools all located in app/code/.
core - Unless the class name starts with Mage or Enterprise for EE version you shouldn't look herecommunity - this hold the community moduleslocal - this holds local extensions (but some community extensions can also be placed here).So you should look in local or community folder for your class. Look for them in that order (first local then community) because in special cases the file can be in both of them but the one in local has priority. (This rarely happens).
An other place the class can be is the lib folder (but this is not the case for you). In there there are core classes like Zend_* or Varien_* and a few others.