On 28/10/2013 7:50 PM, Wolfgang Maier wrote:
imagine you have a flag set somewhere earlier in your code, e.g.,
needs_processing = True
then in a for loop you're processing the elements of an iterable, but the
kind of processing depends on the flag, e.g.,:
for elem in iterable:
if needs_processing:
pre_process(elem) # reformat elem in place
print(elem)
this checks the condition every time through the for loop, even though there
is no chance for needs_processing to change inside the loop, which does not
look very efficient.
There are two approaches I would consider using here:
1. Make pre_process a decorator, and outside of the loop do:
def pre_process_decorator(fn):
def pre_process(x):
# functionality goes here
return fn(x)
return pre_process
if needs_processing:
print = pre_process_decorator(print)
for elem in iterable:
print(elem)
2. Replace the iterable with a generator if the condition is met:
if needs_processing:
iterable = (pre_process(x) for x in iterable)
for elem in iterable:
print(elem)
Personally, I find the 2nd approach clearer.
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