Attila Szabo wrote:
Hi,
def main():
lambda x: 'ABC%s' % str(x)
for k in range(2): exec('print %s' % k)
OK, to no real effect, in main you define an unnamed function that
you can never reference. Pretty silly, but I'll bite.
Next you run run a loop with exec looking like you think it is a
function. In the loop, your "exec" statement does not control
(specify) its access to global and local variables. This could be
a problem if your function were different. The function above does
not do any up-referencing, but:
def main():
def inner():
return k + 1
for k in range(4):
exec 'k = 3 * k'
print k, inner()
What should this do?
If you think you know, how about replacing the exec line with:
exec raw_input('Tricky: ')
You can fix this by controlling what variables the exec can write:
exec 'k = 3 * k' in globals(), locals()
This is why locals() does not do write-back.
The rule below (which was high on the list when searching for exec),
tells the exact rules, the above stuff is just why.
http://www.python.org/doc/2.4/ref/dynamic-features.html
--Scott David Daniels
[EMAIL PROTECTED]
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