Decorator Recipe: Custom Event Binding¶
Step 1¶
Instead of defining the callback and then binding it to the event, we want to do both at the same time:
@downloader.done
def ondone(num_downloaded, time_elapsed):
print "Fetched", num_downloaded, "files in", time_elapsed, "seconds"
To allow the above example to run, add a decorator method called done to class Downloader.
from threading import Thread
import time
class Downloader(object):
def __init__(self, url_list):
self.url_list = url_list
def done(self, func):
"""Add the code for this method"""
def start_downloads(self):
thread = Thread(target=self.download_all)
thread.start()
def download_all(self):
count = 0
start_time = time.time()
for url in self.url_list:
print 'Downloading', url
time.sleep(0.3)
count += 1
end_time = time.time()
self.callback(count, end_time-start_time)
if __name__ == '__main__':
url_list = xrange(1, 13)
downloader = Downloader(url_list)
@downloader.done
def ondone(num_downloaded, time_elapsed):
print "Fetched", num_downloaded, "files in", time_elapsed, "seconds"
downloader.start_downloads()
print 'Waiting for the result...'
Expected result:
Waiting for the result...
Downloading 1
Downloading 2
Downloading 3
Downloading 4
Downloading 5
Downloading 6
Downloading 7
Downloading 8
Downloading 9
Downloading 10
Downloading 11
Downloading 12
Fetched 12 files in 3.60899996758 seconds
Solution: solutions/downloader1.py