Reference python object in an imported function

Question

I have two .py script files. The "main" script will import the second script containing misc "helper" functions.

In the main script, I have set up an object for a SPI interface. I would like to write functions in the imported file that use the SPI interface directly. I'm a noob at this and tried writing and passing in various ways but always get errors.

mainscript.py

import helperfunctions.py as helper

spi = spidev.SpiDev()
spi.open(0, 0)

response = spi.xfer([ ... some data ...])  #this works when
                                           #called from mainscript.py

helper.sendOtherStuff()  #this doesn't work (see helper script below)

helperfunctions.py

def sendOtherStuff():
   #need to somehow reference 'spi.' object from mainscript.py file 
   otherData = ([... some different data ...])
   resp = spi.xfer([otherData])  #this fails because helperfunctions
                                 #apparently doesn't know spi. object
   return resp

I have the same general question often regarding global variable values as well. I'm sure there is a "better" way to do it, but out of convenience for now, I often wish to define some global variables in mainscript.py then reference those globals inside functions of helperfunctions.py. I can't figure a way to do this. Going the other way is easy - declare the globals inside helperfunctions.py then reference them from mainscript.py as helper.variableName, but I don't know how to go the other direction.

Any direction is much appreciated. Thank you.

Answer 1

By my lights the easiest thing to do would be to pass the spi object to the helper function as a parameter:

def sendOtherStuff(spi):
    otherData = ([... some different data ...])  
    return spi.xfer([otherData]) 

Once it's passed in, you can call methods on it in the body of the function. I removed your variable assignment because it seemed redundant.