Difficulty passing integer variables in struct.pack in Python

Question

I am trying to pack two integer variables and write them to the serial port using struct.pack in Python. The variables are defined as integer variables but I keep getting the following error: 'struct.error: required argument is not an integer'

I have been successful at packing actual numbers, just not variables.

my code is

var1 = IntVar()
var2 = IntVar()

I assign integer values using a series of sliders I built in Tkinter and than call the command:

def Pace():

ser.write(struct.pack('!BB',var1,var2) 

I'm sure I am missing something simple, but I can't seem to even force the variables to become integers with Int() or the equivalent.

Any help would be greatly appreciated.

Thank you

Answer 1

IntVar() is not an integer - is a Tkinter object used to notifying observers when it's value changes.

To use it in struct pack you need to retrieve underlying primitive. struct.pack('!BB', var1.get(), var2.get())

.get() method in docs ( emphasis mine ):

The get method returns the current value of the variable, as a Python object. For BooleanVar variables, the returned value is 0 for false, and 1 for true. For DoubleVar variables, the returned value is a Python float. For IntVar, it's an integer . For StringVar, it's either an ASCII string or a Unicode string, depending on the contents.

Answer 2

ser.write(struct.pack('!BB',var1.get(),var2.get()) 

我认为至少...也许只是var1(),var2() ...一段时间以来，因为我搞砸了tkinter