Add routine for using same port again

flash.py

@@ -7,38 +7,56 @@
 
 
 def get_serial_port() -> ListPortInfo:
-    ports: List[ListPortInfo] = comports()
     while True:
+        ports: List[ListPortInfo] = comports()
         for index, port in enumerate(ports):
             print('[%s]\t%s' % (index + 1, port))
-        print('Enter a number between 1 and %s' % len(ports))
+        print('Enter a number between 1 and %s...' % len(ports))
         index = input('> ')
         try:
             index = int(index) - 1
         except ValueError:
-            sys.stderr.write('Input must be a number' + os.linesep + os.linesep)
+            sys.stderr.write('Input must be a number!' + os.linesep + os.linesep)
             continue
         if index not in range(len(ports)):
-            sys.stderr.write('Input must be between 1 and %s' % len(ports)
+            sys.stderr.write('Input must be between 1 and %s!' % len(ports)
                              + os.linesep + os.linesep)
             continue
         else:
             return ports[index]
 
 
+def flash(port: ListPortInfo, file: str):
+    cmd = 'avrdude'
+    param = [
+        '-v', '-p atmega328p', '-c arduino', '-P %s', '-b 115200', '-D',
+        '-U', 'flash:w:%s:i'
+    ]
+    print(' '.join([cmd] + param) % (port.device, file))
+    return os.system(' '.join([cmd] + param) % (port.device, file))
+
 if __name__ == '__main__':
     if len(sys.argv) != 2:
         sys.stderr.write('Usage: python flash.py FILE' + os.linesep)
         sys.exit(2)
 
-    cmd = 'avrdude -v -p atmega328p -c arduino -P %s -b 115200 -D -U ' \
-          'flash:w:%s:i'
+    file = sys.argv[1]
+    port = get_serial_port()
     while True:
-        port = get_serial_port()
-        os.system(cmd % (port.device, sys.argv[1]))
-        print('Enter to continue (next round), anything else to exit')
+        ret = flash(port, file)
+        if ret == 0:
+            print('Success!')
+        else:
+            print('Failed! See output above...')
+        print('Enter to continue, anything else to exit...')
+        print('Notice: If you continue and the same port is still available, '
+            'it will be used again without asking!')
         i = input('> ')
         if i == '':
+            if port.device not in [p.device for p in comports()]:
+                port = get_serial_port()
+            else:
+                print('Using same port again...')
             continue
         else:
             break