# File: callback_demo.py
# To demonstrate implementation and use of callbacks in Python,
# using just plain functions.
# Author: Vasudev Ram
# Copyright 2017 Vasudev Ram
# Web site: https://vasudevram.github.io
# Blog: https://jugad2.blogspot.com
# Product store: https://gumroad.com/vasudevram
from __future__ import print_function
from time import sleep
def callback_a(i, result):
print("Items processed: {}. Running result: {}.".format(i, result))
def square(i):
return i * i
def processor(process, times, report_interval, callback):
print("Entered processor(): times = {}, report_interval = {}, callback = {}".format(
times, report_interval, callback.func_name))
# Can also use callback.__name__ instead of callback.func_name in line above.
result = 0
print("Processing data ...")
for i in range(1, times + 1):
result += process(i)
sleep(1)
if i % report_interval == 0:
# This is the call to the callback function
# that was passed to this function.
callback(i, result)
processor(square, 20, 5, callback_a)
