Scan QR codes automatically and continuously
As Sachin correctly states: If you want to immediately execute any action, the barcode scanner will become the background app -- and your auto[mat] is moved into a garage. If on the other side you want to batch-collect barcodes for later processing: this is possible.

The well-known Barcode Scanner offered for free by the ZXing-Team provides a "bulk scan mode", in which all scanned barcodes will just be stored for later export in e.g. .csv format. You can read more about this in an article on Using Android smartphone to mass import books.