Symfony: sfWidgetFormInputFileEditable, where is the code that removes the file?

by default, when you replace a fil开发者_如何学JAVAe using sfWidgetFormInputFileEditable, the old file is removed from your hard disk.

Where is that code that removes the file??

Javi

sf 1.3

symfony/lib/plugins/sfDoctrinePlugin/lib/form/ sfFormDoctrine.class.php