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The interface I would want would be something like:     my @new= ConvertTo( $toUnits, $fromUnits, @old );
which would convert the numbers in @old from $fromUnits to $toUnits and return the results. So:

# <--------- inches ---------><----- ft -----> my @inches= ConvertTo( 'in', 'ft', 1, 2, 3 ); # @inches is now ( 12, 24, 36 )
Note that it is "to" followed by "from" so the unit name is closest to the numbers that are/will be in those units.

If I want to do a lot of conversions but not all at once, then:

my $toInFromFt= ConvertTo( 'in', 'ft' ); while( <IN> ) { chomp; print OUT $toInFromFt->($_), $/; }
And I'd probably support aliases for units and include a "long alias" for every unit: "inch", "feet", "meter", "centimeter", "Centigrade", "Farenheit", "Kelvin", "second", "hour", etc. just to avoid confusion.

I'd probably put the unit data after __DATA__ so you could just append more units to be able to support them.

The "all possible conversions" is interesting for interactive exploration, but I don't see nearly as much use for it as requesting a specific conversion.

For finding the conversion, I'd look for a direct conversion, but if there isn't one, form the list of all possible conversions and then repeat for each of those:

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 %table; for my $conv ( @table ) { my( $from, $to, $conv, $rev )= @$conv; if( exists $table{$from}{$to} ) { warn "Duplicate conversions to $to from $from.\n"; } $table{$from}{$to}= $conv; if( $rev ) { if( exists $table{$from}{$to} ) { warn "Duplicate conversions to $from from $to.\n"; } $table{$to}{$from}= $rev; } } # Handle reverse conversions when a better one isn't provided: for my $conv ( @table ) { my( $from, $to, $conv )= @$conv; if( ! ref($conv) && ! exists $table{$to}{$from} ) { $table{$to}{$from}= sub { $_[0] / $conv }; } } sub FindConversionPathTo { my( $dest, $source )= @_; my( @sol ); $source= { $source => "$source " }; while( ! @sol ) { for my $src ( keys %sources ) { if( exists $table{$src}{$dest} ) { $source{$src} .= "$dest "; push @sol, $src; } else { for my $dest ( keys %{$table{$src} ) { if( ! exists $source{$dest} ) { $source{$dest}= $source{$src} . "$dest "; } } } } } # Pick one of the solutions at random: (: return split ' ', (@source{@sol})[rand @sol]; }
Untested (I hope you don't mind).

        - tye

In reply to (tye)Re4: The Definitive Unit Conversion Script by tye
in thread The Definitive Unit Conversion Script by Aristotle

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    [Corion]: erix: Ah. I use where 1 = 0 for queries where I only am interested in the structure ;)
    [erix]: 1=0 is as short as TOP :)
    [erix]: "code of someone that died" -- kinda nice if your code stops working too
    [erix]: hard to implement, hmm
    [Corion]: erix: Well, they also seem to have changed the server, or some software, or whatever, and seem to be in the process of changing the DB schema from having the "username" as primary key to something else.
    [Corion]: Far too many things being done at once, or maybe only now has it become apparent that nobody knows that piece of software anymore

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