As others have mentioned, it's handy to capture min and max logic in subroutines for reuse. Most times, if you have a max subroutine, for example, it will take an array and return the maximum element. That's great if you want to hold all of your values in memory, but what if you don't? What if you want to compute your maximum iteratively, e.g., one number at a time while reading from a file?

As I offered in Re: getting the highest value in a simpler way, we can encapsulate our logic inside of a closure-based factory function that makes "maximum finders":

    sub make_max_finder {
        my $max;
        sub {
            for (@_) { $max = $_ if !defined $max || $_ > $max }
            $max;
        }
    }
[download]

The nice thing about this approach is that the logic is captured in one place and yet we can use it both on big arrays and upon iterated-over data. The array method:

    make_max_finder->(1..10); # 10
[download]

The iterative, light-on-memory method:

    my $max_finder = make_max_finder();
    $max_finder->($_) while <>;
    $max_finder->();  # retrieve maximum
[download]

Cheers,
Tom

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