automatically when the program terminates without relying on the application
making an explicit call into this module at termination. ::
+ infile = open("/tmp/counter")
try:
- _count = int(open("/tmp/counter").read())
+ _count = int(infile.read())
except IOError:
_count = 0
+ finally:
+ infile.close()
+
def incrcounter(n):
global _count
_count = _count + n
def savecounter():
- open("/tmp/counter", "w").write("%d" % _count)
+ with open("/tmp/counter", "w") as outfile:
+ outfile.write("%d" % _count)
import atexit
atexit.register(savecounter)
def do_playback(self, arg):
'Playback commands from a file: PLAYBACK rose.cmd'
self.close()
- cmds = open(arg).read().splitlines()
- self.cmdqueue.extend(cmds)
+ with open(arg) as f:
+ self.cmdqueue.extend(f.read().splitlines())
def precmd(self, line):
line = line.lower()
if self.file and 'playback' not in line:
def tail(filename, n=10):
'Return the last n lines of a file'
- return deque(open(filename), n)
+ with open(filename) as f:
+ return deque(f, n)
Another approach to using deques is to maintain a sequence of recently
added elements by appending to the right and popping to the left::
# we're passing these as arguments to the diff function
fromdate = time.ctime(os.stat(fromfile).st_mtime)
todate = time.ctime(os.stat(tofile).st_mtime)
- fromlines = open(fromfile, 'U').readlines()
- tolines = open(tofile, 'U').readlines()
+ with open(fromlines) as fromf, open(tofile) as tof:
+ fromlines, tolines = list(fromf), list(tof)
if options.u:
diff = difflib.unified_diff(fromlines, tolines, fromfile, tofile,
import struct
- data = open('myfile.zip', 'rb').read()
+ with open('myfile.zip', 'rb') as f:
+ data = f.read()
+
start = 0
for i in range(3): # show the first 3 file headers
start += 14