Duncan Booth wrote:
/ class CallableOnlyOnce(object):
/ def __init__(self, func):
self.func = func
def __call__(self):
f = self.func
if f:
self.func = None
return f()
/ def callonce(func):
/ return CallableOnlyOnce(func)
/ @callonce
/def t2():
print "T2 called"
/ t2()
/T2 called
/ t2()
/>>>/ /
You don't need both the CallableOnlyOnce class and the callonce function. How
about the following ... just for fun, it provides the extra functionality of
counting the number of times a function was *called*, even though it was
*executed* only once:
--------------------------
class ExecOnlyOnce(object):
def __init__(self, f):
print "Making function '%s' into a one-shot" % f.__name__
self.func = f
self.func_call_count = 0
def __call__(self):
print "Calling one-shot function:", self.func.__name__
self.func_call_count += 1
if self.func_call_count == 1:
return self.func()
@ExecOnlyOnce
def func1():
print " inside original function: func1"
return 111
@ExecOnlyOnce
def func2():
print " inside original function: func2"
return 222
# run the functions
# collect return values just once for each function
r1 = func1()
r2 = func2()
func1()
func1()
func2()
func1()
# summary
print "\nSummary:"
for fn in (func1, func2):
print "Function '%s' was called %d times" % (fn.func.__name__,
fn.func_call_count)
print "r1 =", r1
print "r2 =", r2
--------------------------
Output:
Making function 'func1' into a one-shot
Making function 'func2' into a one-shot
Calling one-shot function: func1
inside original function: func1
Calling one-shot function: func2
inside original function: func2
Calling one-shot function: func1
Calling one-shot function: func1
Calling one-shot function: func2
Calling one-shot function: func1
Summary:
Function 'func1' was called 4 times
Function 'func2' was called 2 times
r1 = 111
r2 = 222
-John
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