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Re^3: Real life uses for closures.

by runrig (Abbot)
on Feb 13, 2013 at 00:36 UTC ( #1018470=note: print w/ replies, xml ) Need Help??

in reply to Re^2: Real life uses for closures.
in thread Real life uses for closures.

Heh, reading that link, one of the basic things I've used closures for lately is filtering a list in different ways. I had one utility function that goes into a loop parsing email files from a directory (and if successful, finally returning the attachments from the one you want according to some parameters) and skipping files that it's already seen before. Then I found that in some particular case I needed to call the function multiple times and have it remember what it had seen from the previous call. So I turned the filtering function into a parameter, allowing you to maintain the hash of 'seen' email files outside of the loop in the main function (but keeping the original behaviour by default, which is what I want most of the time). Pretty basic example...but there it is.

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