Viewing file:  counter.py (1.47 KB) -rw-r--r--
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# -*- Mode: Python -*-
# It is tempting to add an __int__ method to this class, but it's not
# a good idea. This class tries to gracefully handle integer
# overflow, and to hide this detail from both the programmer and the
# user. Note that the __str__ method can be relied on for printing out
# the value of a counter:
#
# >>> print 'Total Client: %s' % self.total_clients
#
# If you need to do arithmetic with the value, then use the 'as_long'
# method, the use of long arithmetic is a reminder that the counter
# will overflow.
from supervisor.compat import long
class counter:
"""general-purpose counter"""
def __init__ (self, initial_value=0):
self.value = initial_value
def increment (self, delta=1):
result = self.value
try:
self.value = self.value + delta
except OverflowError:
self.value = long(self.value) + delta
return result
def decrement (self, delta=1):
result = self.value
try:
self.value = self.value - delta
except OverflowError:
self.value = long(self.value) - delta
return result
def as_long (self):
return long(self.value)
def __nonzero__ (self):
return self.value != 0
__bool__ = __nonzero__
def __repr__ (self):
return '<counter value=%s at %x>' % (self.value, id(self))
def __str__ (self):
s = str(long(self.value))
if s[-1:] == 'L':
s = s[:-1]
return s
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