CODEWITHSUNDEEP
pythonrecursion
TheHidden
TheHidden

Reputation: 592

cleaning up function looping

I am looping a function in python as I created my own constant listener. My question is how can I ensure I don't overflow / crash? Logically this is telling me I am leaving a lot of open functions in the background. Once parameters of my application are met I exit(0) for a clean shut down. but how can I ensure this doesn't eat up memory?

This code works fine btw, but I am simply trying to improve it because it feels really wrong to me that I am calling the function within its self without closing the previous use of it and it just feels dirty. constructive comments please.

e.g. (this is now my actual code)

import serial
import sys
import time
def enterdata():
     ser = serial.Serial(sys.argv[1], sys.argv[2])
     ser.write("\r")
     time.sleep(0.5)
     while True:
         data = ser.read(ser.inWaiting())
         if (len(data) > 0):
             a = []
             for i in range(len(data)):
                 a.append(data[i])
                 if "Please press Enter to activate this console." in "".join(a):
                     print ("1")
                     exit(0)
                     break
      ser.close()
      enterdata()
ser = serial.Serial(sys.argv[1], sys.argv[2])
ser.write("\r\n")
enterdata()

NEW VERSION SO FAR FROM POSTS MADE:

import serial
import sys
import time
def enterdata():
 ser = serial.Serial(sys.argv[1], sys.argv[2])
 ser.write("\r")
 time.sleep(0.5)
 while True:
  data = ser.read(ser.inWaiting())
  if (len(data) > 0):
   a = []
   for i in range(len(data)):
    a.append(data[i])
    if "Please press Enter to activate this console." in "".join(a):
     print ('1')
     return True
     exit(0)
   break
 ser.close()
ser = serial.Serial(sys.argv[1], sys.argv[2])
ser.write("\r\n")
state = False
while state is not True:
 state = enterdata()

Upvotes: 0

Views: 79

Answers (1)

Rockybilly
Rockybilly

Reputation: 4510

This code you showed will give a "RuntimeError: maximum recursion depth exceeded" Error because of Python sets a default value for how many recursions can occur in one function at a time.

Any yours is infinite and definitely will cause problems even if you change this default limit.

Why not make a loop yourself and call the function at will ?

found = False
while not found:
    extracted_data = lookfordata()
    if extracted_data == "I want it to be equal to this":
        found = True

I see you edited the post. Whatever you are trying to do, that method is not efficent, not recommended and not pretty. All the good reasons not to use it.

Imagine that you will handle some data larger than you are using now, you won't know if the recursion stopping condition will come to pass before you exceed the limit. It's also no use to increase limit all the time you encounter a bigger data. I think it should be any programmer's goal to avoid repetition and coming up with programs that can handle any type of unexpected input.

You updated your post again. This way of input handling is much better than raw recursion. Just to mention, instead of;

for i in range(len(data)):
    a.append(data[i])

use

for i in data:
    a.append(i)

Upvotes: 2

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