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#!/usr/bin/perl -w use strict; use Getopt::Std; sub conv { my ($val, $fac) = @_; ref $fac ? $fac->[0]->($val) : $val * $fac; } sub reverse_conv { my ($val, $fac) = @_; ref $fac ? $fac->[1]->($val) : $val / $fac; } use constant SRC => 0; use constant DST => 1; use constant FAC => 2; my @table = ( #### temperature [ c => f => [ sub { ($_[0] * 9/5) + 32 }, sub { ($_[0] - 32) * 5/9 }, ]], [ c => k => [ sub { $_[0] + 273.16 }, sub { $_[0] - 273.16 }, ]], #### mass/weight [ kg => g => 1000 ], [ floz => g => 30 ], [ lbs => kg => 0.4536 ], #### distance [ ft => m => 0.3048 ], [ ft => in => 12 ], [ in => cm => 2.54 ], [ m => cm => 100 ], [ yd => m => 0.9144 ], [ km => m => 1000 ], [ mile => km => 1.609347 ], ); my @unit = sort keys %{{ map +($_->[SRC] => 1, $_->[DST] => 1), @table }}; die << "END_USAGE" unless getopts('ap:', \my %opt) and @ARGV and (0 == + @ARGV % 2); usage: unitconv [-a] [-p precision] <val> <unit> [<val> <unit> [..]] -p the number of decimal places [default: 2] -a force all possible conversions to be shown, even if insufficient display precision truncates the value to 0 <unit> can be one of: @unit Results will be printed on one line per input val/unit pair. END_USAGE my $prec = $opt{p} || 2; while(@ARGV) { my (%val, $keys_before) = reverse splice @ARGV, 0, 2; do { $keys_before = keys %val; for(@table) { $val{$_->[DST]} = conv($val{$_->[SRC]}, $_->[FAC]) if exists $val{$_->[SRC]} and not exists $val{$_->[DST]}; $val{$_->[SRC]} = reverse_conv($val{$_->[DST]}, $_->[FAC]) if exists $val{$_->[DST]} and not exists $val{$_->[SRC]}; } } until ($keys_before == keys %val); unless($opt{a}) { sprintf("%.*f", $prec, $val{$_}) == 0 and delete $val{$_} for keys %val; } printf "% 8.${prec}f %s " x keys(%val) . "\n", map +($val{$_} => $_), sort keys %val; }

In reply to The Definitive Unit Conversion Script by Aristotle

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    [Corion]: Meh. I need to find myself a better "programming" feed than r/programming (which is just HackerNews reposts and advertisements, very little code). Maybe I should select a list of links that I liked on r/programming and then google for ...
    [Corion]: ... an aggregator site that also listed (ideally) all of these links once. And maybe also have an exclude list to blacklist some of the most spammy links that the site may have never mentioned at all
    [marto]: I gave up reading HN at all, and feel much better for it :P
    [Corion]: Now, how to best automate that Google search ... :-)
    [Corion]: marto: Yeah, I'm also short of not reading it at all. I already stopped reading it in the morning because it gave me a foul mood.
    [Corion]: The good posts on HN are the non-computing posts. Most of the other stuff is maybe relevant to you if you are 20 and live in Silicon Valley...
    [Corion]: Two attributes that don't describe me.
    [Corion]: Maybe I should also write a curator for HN or simply not read it anymore, like you do.

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