...at least, I think that I'm having a problem understanding the way
closures work.
I'm trying to define a function for an object which will take certain
objects from the parent scope at the time that function is defined.
For some reason, if I do this function definition in a loop, the
locals given by that function (is this a closure?) are changed each
iteration of the loop, whereas if the function definition is isn't
looped over, I get the behavior I desire. Can anyone provide any
insight for me?
thanks,
-tom!
First, the output:
Test 1 doesn't work the way I would expect:
Test 4 says, "Test 0"
Test 4 says, "Test 1"
Test 4 says, "Test 2"
Test 4 says, "Test 3"
Test 4 says, "Test 4"
...but test 2 does?
Test 0 says, "Test 0"
Test 1 says, "Test 1"
Test 2 says, "Test 2"
Test 3 says, "Test 3"
Test 4 says, "Test 4"
Next, the program:
class Test:
def __init__(self, name):
self.name = name
def DoCall(self):
self.ExternalCall(self.name)
# The first test.
def CreateTests1(count):
tests = []
for i in xrange(count):
name = 'Test %d' % i
t = Test(name)
tests.append(t)
def ExCall(text):
print '%s says, "%s"' % (name, text)
t.ExternalCall = ExCall
return tests
# The second test.
def CreateTests2(count):
tests = []
for i in xrange(count):
t = CreateTest(i)
tests.append(t)
return tests
def CreateTest(index):
name = 'Test %d' % index
t = Test(name)
def ExCall(text):
print '%s says, "%s"' % (name, text)
t.ExternalCall = ExCall
return t
print 'Test 1 doesn\'t work the way I would expect:'
for t in CreateTests1(5):
t.DoCall()
print '\n...but test 2 does?'
for t in CreateTests2(5):
t.DoCall()
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