Removed unneeded member variables

hpib.py

@@ -16,6 +16,9 @@ class PortDevice(object):
 
 
 class PrologixGpibUsb(PortDevice):
+    _serialPort = None
+    _hpib_address = -1
+
     def __init__(self, port="", timeout=1, portFormat="%d", maxDeviceNum=9, verbose=False,
                  findDevices=False):
         if port == "":
@@ -37,7 +40,6 @@ class PrologixGpibUsb(PortDevice):
         if not self._rematch:
             raise ValueError(port)
 
-        self._serialPort = None
         while int(self._rematch.group(2)) < maxDeviceNum:
             if verbose:
                 print "trying ", port
@@ -60,36 +62,33 @@ class PrologixGpibUsb(PortDevice):
         if findDevices:
             self._devices = []
             for self._hpib_address in range(0, 31):
-                self._commandStr = "++addr " + str(self._hpib_address) + chr(10) + \
+                commandStr = "++addr " + str(self._hpib_address) + chr(10) + \
                                    "*idn?" + chr(10) + \
                                    "++read" + chr(10)
-                self._serialPort.write(self._commandStr)
-                self._returnStr = self._serialPort.readline()
-                if self._returnStr != "":
-                    self._devices += [self._hpib_address, self._returnStr]
+                self._serialPort.write(commandStr)
+                returnStr = self._serialPort.readline()
+                if returnStr != "":
+                    self._devices += [self._hpib_address, returnStr]
         else:
             self._devices = "Not scanned."
         self._hpib_address = -1
 
     def command(self, hpib_address, command):
         if hpib_address != self._hpib_address:
-            self._commandStr = "++addr " + str(hpib_address) + chr(10)
+            command = "++addr " + str(hpib_address) + chr(10) + command
             self._hpib_address = hpib_address
-        else:
-            self._commandStr = ""
-        self._commandStr += command + chr(10)
-        self._commandCount = self._serialPort.write(self._commandStr)
+
+        self._serialPort.write(command + chr(10))
 
     def query(self, hpib_address, query, count=80):
         if hpib_address != self._hpib_address:
-            self._commandStr = "++addr " + str(hpib_address) + chr(10)
+            query = "++addr " + str(hpib_address) + chr(10) + query
             self._hpib_address = hpib_address
-        else:
-            self._commandStr = ""
-        self._commandStr += query + chr(10) + "++read eoi" + chr(10)
-        self._commandCount = self._serialPort.write(self._commandStr)
-        self._returnStr = self._serialPort.readline()
-        return self._returnStr[:-1]
+
+        query += chr(10) + "++read eoi" + chr(10)
+        self._serialPort.write(query)
+        line = self._serialPort.readline()
+        return line[:-1]
 
     def set_local(self, hpib_address):
         # self._commandStr = "++addr "+str(hpib_address)+chr(10)+"loc "+str(hpib_address)+chr(10)

test/test_hpib.py

@@ -98,6 +98,30 @@ class PrologixGpibUsbTest(unittest.TestCase):
         with self.assertRaises(ValueError):
             hpib.PrologixGpibUsb(port="device")
 
+    def test_command_prepend_plusplus_addr_if_new_address(self):
+        address = 2
+        command = "command"
+        write_mock = self.serial_mock.return_value.write
+
+        usb = hpib.PrologixGpibUsb()
+
+        usb.command(address, command)
+
+        write_mock.assert_called_with("++addr " + str(address) + chr(10) + command + chr(10))
+
+    def test_query_prepend_plusplus_addr_if_new_address(self):
+        address = 2
+        query = "query"
+        write_mock = self.serial_mock.return_value.write
+
+        usb = hpib.PrologixGpibUsb()
+
+        usb.query(address, query)
+
+        write_mock.assert_called_with("++addr " + str(address) + chr(10) +
+                                      query + chr(10) +
+                                      "++read eoi" + chr(10))
+
 
 if __name__ == '__main__':
     unittest.main()