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It's lovely to collaboratively code with fellow Monks. Last localtime-night in the cb Brer' broquaint and I wrote this subroutine which I've decided to name max_strl (a kind of C-ish name for a Perl identifier, granted).

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Usage:

Pass the first argument/parameter as a hash reference. If any additional argument is passed the function will return the length of the longest key instead of the length of the longest value.

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Update: Wed Aug 20 2003 23:08 UTC

Incorporated diotalevi's suggestion so that we can pass a blessed object that is a (isa()) hashref, as well.

 # last mod: Wed Aug 20 2003 23:08 UTC
 # by [Intrepid], with quality tweaking by [broquaint] ;-)
sub max_strl {
     UNIVERSAL::isa( (my $h = shift) , 'HASH')
       or die "Must pass a hashref!\n";
     my $ml = 0; length > $ml and $ml = length
           for ( @_ ? keys %$h : values %$h );
     return $ml;
}
[download]

Applications:

Although it's a very short piece of code (made even more concise due to broquaint's economy of style), this is IMHO a broadly useful bit. One general area where it is likely to be helpful concerns those times in which we are trying to exercize a little more fine-grained control over spacing in our screen real-estate. Something a little more precise than just sprinkling our output format with TABs ...

For (a dumb) example, to pretty-printout a hash of varying-length items like this, with stuff on both front and behind:

#!/usr/bin/env perl

use strict;
use warnings;

$\ = "\n";
my $i = 'A';
my(%hash) = map(($i++, $_), split(/:/, $ENV{'PATH'}, 0));
my $maxl = max_strl(\%hash) + 5;

my $format1 = "PathEle %3s%${maxl}s% 10u Kb used";
foreach (sort keys %hash) {
    my $use_of_disk = "du -ks $hash{$_}";
    printf "$format1\n", $_, $hash{$_}, (split /\s+/,`$use_of_disk`)[0
+];
}
exit 0;
[download]

Using max_strl with printf() is just the start. Your imagination is the only limit! {grin}.