examples/units.pl

   1 use v6;
   2
   3 class Unit {
   4     has $.q   is rw;
   5
   6     method set    ($self: Num $value) { $.q = $value; $self; };
   7     multi method string ($self:) {$self.q ~ $self.abbreviation; }
   8     multi method string ($self: Num $prec) {
   9         return $self.q.fmt('%.' ~ $prec ~ 'f') ~ $self.abbreviation;
  10     }
  11
  12     method toBase($self:)     { $.q * $self.baseFactor }
  13     method fromBase($self:)   { $.q / $self.baseFactor }
  14
  15     method setFromBase($self: Num $value) { $.q = $value / $self.baseFactor; }
  16     method baseFactor() { 1; }
  17 }
  18
  19 multi sub infix:<+>   (Unit $a, Unit $b) {
  20    die unless $a.type eq $b.type;
  21    my $new = $a.clone();
  22    # wierd hack around a wierd error.
  23    my $aVal = $a.toBase();
  24    my $bVal = $b.toBase();
  25    $new.setFromBase( $aVal + $bVal);
  26    return $new;
  27 }
  28
  29 multi sub infix:<->   (Unit $a, Unit $b) {
  30    my $new = $a.clone();
  31    # wierd hack around a wierd error.
  32    my $aVal = $a.toBase();
  33    my $bVal = $b.toBase();
  34    $new.setFromBase( $aVal - $bVal);
  35    return $new;
  36 }
  37
  38 class Distance is Unit { method type () { 'distance'} }
  39
  40 multi sub postfix:<ft> (Num $value) { Feet.new().set($value)  }
  41 class Feet is Distance {
  42     method abbreviation () { "ft" };
  43     method baseFactor   () { 0.3048 };
  44 }
  45
  46 # not m, as that's taken by m//
  47 multi sub postfix:<m> (Num $value) { Meter.new().set($value)  }
  48 class Meter is Distance {
  49     method abbreviation () { "m" };
  50     # no base factor because it IS the base Unit
  51 }
  52
  53 multi sub postfix:<km> (Num $value) { Kilometer.new().set($value)  }
  54 class Kilometer is Distance {
  55     method abbreviation () { "km" };
  56     method baseFactor    () { 1000 };
  57 }
  58
  59 multi sub prefix:<~> (Unit $unit)   { $unit.string; }
  60 #multi sub infix:<`>  (Int $value, Unit $unit) { $unit.set($value); };
  61
  62 my $feet  = 5ft;
  63 my $meter = 6m;
  64 say $feet.string();
  65 say $meter.string();
  66 # my $z = $x.to($y);
  67 # say $z.string;
  68
  69 my $add = $feet + $meter;
  70 say $add.string(2);
  71
  72 my $add2 = $meter + $feet;
  73 say ~$add2;
  74
  75 my $sub = $meter - $feet;
  76 say ~$sub;
  77
  78 my $kilometer = 1000km;
  79 $add = $kilometer + 90ft;
  80 say $add.string(2);
  81
  82 my $add = 1ft + 1m;
  83 say $add.string(2);
  84