extracted port name validation to a method

hpib.py

@@ -24,13 +24,11 @@ class PrologixGpibUsb(PortDevice):
         if port == "":
             maxDeviceNum, port, portFormat = self._set_default_platform_values()
 
+        self._validate_port(port)
+
         if verbose:
             print "Looking for ports such as %s in range %d on %s" % \
                   ( port, maxDeviceNum, platform.system() )
-        self._rematch=re.search(r"(/dev/tty.*[^0-9])([0-9]+$)",port)
-
-        if not self._rematch:
-            raise ValueError(port)
 
         while int(self._rematch.group(2)) < maxDeviceNum:
             if verbose:
@@ -39,8 +37,8 @@ class PrologixGpibUsb(PortDevice):
                 self._serialPort = serial.Serial(port,timeout=timeout)
                 break
             except serial.SerialException:
-                port=self._rematch.group(1) +\
-                      (portFormat % (int(self._rematch.group(2))+1))
+                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")
@@ -55,8 +53,8 @@ class PrologixGpibUsb(PortDevice):
             self._devices = []
             for self._hpib_address in range(0, 31):
                 commandStr = "++addr " + str(self._hpib_address) + chr(10) + \
-                                   "*idn?" + chr(10) + \
-                                   "++read" + chr(10)
+                             "*idn?" + chr(10) + \
+                             "++read" + chr(10)
                 self._serialPort.write(commandStr)
                 returnStr = self._serialPort.readline()
                 if returnStr != "":
@@ -65,6 +63,11 @@ class PrologixGpibUsb(PortDevice):
             self._devices = "Not scanned."
         self._hpib_address = -1
 
+    def _validate_port(self, port):
+        self._rematch = re.search(r"(/dev/tty.*[^0-9])([0-9]+$)", port)
+        if not self._rematch:
+            raise ValueError(port)
+
     def _set_default_platform_values(self):
         if platform.system() == "Linux":
             port = "/dev/ttyUSB0"