CODEWITHSUNDEEP
pythonpython-2.7
John Roberts
John Roberts

Reputation: 133

Time variable to timeout if condition

I have the following Python code that has an if condition that checks to see if current_ident is the same as last ident and if so then not print the current_ident value.

What I would like to do is add a time-out to this check so only check to see if the current and last is the same for 7 seconds after that let it print if it's the same. I'm thinking possible by adding a global variable last_read which saves the time and then maybe use something like last_read + [timeout] > [current_time]?

from nfc import ContactlessFrontend
from time import sleep

ident = '' 

def connected(tag):
    global ident
    current_ident = ''.join('{:02x}'.format(ord(c)) for c in tag.identifier)
    if current_ident != ident:
        print(current_ident)
        ident = current_ident
    return False

clf = ContactlessFrontend('usb')
while True:
    clf.connect(rdwr={'on-connect': connected})
    sleep(1)

Upvotes: 0

Views: 211

Answers (1)

quamrana
quamrana

Reputation: 39364

You should be able to keep a track of time as well as the last ident:

from nfc import ContactlessFrontend
from time import sleep
import time

ident = '' 
next_time = None

def connected(tag):
    global ident
    global next_time
    current_ident = ''.join('{:02x}'.format(ord(c)) for c in tag.identifier)
    if current_ident != ident:
        next_time = time.time() + 7
        print(current_ident)  # Brand new ident
        ident = current_ident
    elif time.time() > next_time:
        next_time = time.time() + 7
        print(current_ident)  # Repeated ident allowed
    # else:  # disallow repeated ident
    return False

clf = ContactlessFrontend('usb')
while True:
    clf.connect(rdwr={'on-connect': connected})
    sleep(1)

Upvotes: 1

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