extracted available port search to a method

hpib.py

@@ -30,18 +30,8 @@ class PrologixGpibUsb(PortDevice):
             print "Looking for ports such as %s in range %d on %s" % \
                   ( port, maxDeviceNum, platform.system() )
 
-        while int(self._rematch.group(2)) < maxDeviceNum:
-            if verbose:
-                print "trying ", port
-            try:
-                self._serialPort = serial.Serial(port,timeout=timeout)
-                break
-            except serial.SerialException:
-                port=self._rematch.group(1) + \
-                     (portFormat % (int(self._rematch.group(2))+1))
-                self._rematch=re.search("(/dev/tty.*[^0-9])([0-9]+$)",port)
-        if self._serialPort==None:
-            raise serial.SerialException("Cannot find port")
+        self._find_available_port(maxDeviceNum, port, portFormat, timeout, verbose)
+
         self._serialPort.write("++savecfg 0" + chr(10))
         self._serialPort.write("++auto 0" + chr(10))
         self._serialPort.write("++eoi 1" + chr(10))
@@ -63,6 +53,19 @@ class PrologixGpibUsb(PortDevice):
             self._devices = "Not scanned."
         self._hpib_address = -1
 
+    def _find_available_port(self, maxDeviceNum, port, portFormat, timeout, verbose):
+        while int(self._rematch.group(2)) < maxDeviceNum:
+            if verbose:
+                print "trying ", port
+            try:
+                self._serialPort = serial.Serial(port, timeout=timeout)
+                break
+            except serial.SerialException:
+                port = self._rematch.group(1) + (portFormat % (int(self._rematch.group(2)) + 1))
+                self._rematch = re.search("(/dev/tty.*[^0-9])([0-9]+$)", port)
+        if self._serialPort is None:
+            raise serial.SerialException("Cannot find port")
+
     def _validate_port(self, port):
         self._rematch = re.search(r"(/dev/tty.*[^0-9])([0-9]+$)", port)
         if not self._rematch: