Dynamic variable from function in Python

Question

var 1 is constantly changing with every new line that is written in the csv file. Any suggestion how can I get the value outside of the function. This example does not work for me. I updated my code and added second function which is exactly the same but is reading another file. Now I only get print from the first function only. If I disable the first function I can get the print from the second function. Is there a way to print both of them or maybe three or four if I add later new functions ?

import sys
import time
import datetime
import os
class Application():
 def loop_one(self):
 filename = 'Test.csv'
 mycsv = open(filename, 'r')
 mycsv.seek(0, os.SEEK_END)
 while 1:
 time.sleep(1)
 where = mycsv.tell()
 line = mycsv.readline()
 if not line:
 mycsv.seek(where)
 else:
 arr_line = line.split(',')
 var1 = arr_line[5]
 mydate = datetime.datetime.now()
 print var1, mydate.strftime("%H:%M:%S:%f")
 return var1
 def loop_two(self):
 filename2 = 'Test2.csv'
 mycsv2 = open(filename2, 'r')
 mycsv2.seek(0, os.SEEK_END)
 while 1:
 time2.sleep(1)
 where2 = mycsv2.tell()
 line2 = mycsv2.readline()
 if not line2:
 mycsv2.seek(where2)
 else:
 arr_line2 = line2.split(',')
 var2 = arr_line2[5]
 mydate2 = datetime.datetime.now()
 print var2, mydate.strftime("%H:%M:%S:%f")
 return var2
s = Application()
var1 = s.loop_one()
var2 = s.loop_two()

• TigerhawkT3: Have you tried saving a reference? var1 = s.loop_one()
• manev: I tried var1 = s.loop_one() and then print var1 but got nothing
• Kevin M Granger: Are you sure your indentation is correct? Should your if and else statement be within the while loop?
• manev: Yes that was the problem. Thanks..

Answer 1

You can declare a variable inside the init function so you can use that anywhere

class A(object):
 def __init__(self):
 self.x = 'Hello'
 def method_a(self, foo):
 print self.x + ' ' + foo

In your case you can do something like this (not tested)

class Application():
 def __init__(self):
 self.filename = 'Test.csv'
 self.mycsv = open(self.filename, 'r')
 self.mycsv.seek(0, os.SEEK_END)
 self.var1 = ''
 def loop_one(self):
 while 1:
 time.sleep(1)
 where = self.mycsv.tell()
 line = self.mycsv.readline()
 if not line:
 self.mycsv.seek(where)
 # you need a break here or somewhere :D
 else:
 arr_line = line.split(',')
 self.var1 = arr_line[5]
 mydate = datetime.datetime.now()
 print self.var1, mydate.strftime("%H:%M:%S:%f")
 return self.var1
s = Application()
s.loop_one()

Answer 2

You have move your if else block inside the for loop otherwise your code will stuck in infinite loop.

import sys
import time
import datetime
import os
class Application():
 def loop_one(self):
 filename = 'Test.csv'
 mycsv = open(filename, 'r')
 mycsv.seek(0, os.SEEK_END)
 while 1:
 time.sleep(1)
 where = mycsv.tell()
 line = mycsv.readline()
 if not line:
 mycsv.seek(where)
 else:
 arr_line = line.split(',')
 var1 = arr_line[5]
 mydate = datetime.datetime.now()
 print var1, mydate.strftime("%H:%M:%S:%f")
 return var1
s = Application()
s.loop_one()

Answer 3

Accessing var1 outside the function

class Application:
 var1 = None
 def loop_one(self):
 # Code
 while True:
 # Your code
 if not line:
 # Code
 else:
 global var1
 # Code
 var1 = arr_line[5]
 # Then you can access it via
 def show():
 print(var1)