second version avoids double using "default_option_" string but, in my opinion, is less straightforward than my original.

Compare 
for ( grep /^default_option_/, keys %def ) {

   $s{ (split /_/, $_, 2)[-1] } = $def{ $_ };
}

[download]
with original 
foreach (map { /^default_option_(.*)/ ? $1 : () } keys %def) {
    $s{"option_$_"} = $def{"default_option_$_"};
}

[download]
Second case more distinctly highlights idea to use the subpart of key string as a new key. I wished to have something like 
for (grep /^default_option_(.*)/, keys %def) {
    $s{"option_$1"} = $def{$_};
}

[download]
or even more short 
$s{"option_$1"} = $def{$_} for (grep /^default_option_(.*)/, keys %def
+);

[download]

Of course the last 2 solutions are incorrect. But if some monk knows how to achieve such level of laconism and clearness in one that would be a great pattern.

Anyway I like your solutions for custom, rare cases. But I need a nice looking, straightforward and short version for everyday use. Of course if it exists in Perl 5 universe.

Another problem is that your last solution truncates hash if it has data. It's not appropriate for me. Though I'm not sure if moritz's version does this.

FYI: I've just registered. And this is my post

In reply to Re^3: get solution as short as possible by dexahex
in thread get solution as short as possible by Anonymous Monk

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