ruby-units.rb in ruby-units-0.3.3

- old
+ new

@@ -1,10 +1,10 @@
 require 'mathn'
 require 'rational'
 require 'date'
 require 'parsedate'
-# = Ruby Units 0.3.1
+# = Ruby Units 0.3.3
 #
 # Copyright 2006 by Kevin C. Olbrich, Ph.D.
 # 
 # See http://rubyforge.org/ruby-units/
 #
@@ -38,11 +38,11 @@
 #  end
 #  Unit.setup
 class Unit < Numeric
   require 'units'
   # pre-generate hashes from unit definitions for performance.  
-  VERSION = '0.3.0'
+  VERSION = '0.3.3'
   @@USER_DEFINITIONS = {}
   @@PREFIX_VALUES = {}
   @@PREFIX_MAP = {}
   @@UNIT_MAP = {}
   @@UNIT_VALUES = {}
@@ -127,12 +127,11 @@
       end
       @@OUTPUT_MAP[key]=value[0][0]        
     end
     @@PREFIX_REGEX = @@PREFIX_MAP.keys.sort_by {|prefix| prefix.length}.reverse.join('|')
     @@UNIT_REGEX = @@UNIT_MAP.keys.sort_by {|unit| unit.length}.reverse.join('|')
-    @@UNIT_MATCH_REGEX = /(#{@@PREFIX_REGEX})*?(#{@@UNIT_REGEX})\b/  
-    
+    @@UNIT_MATCH_REGEX = /(#{@@PREFIX_REGEX})*?(#{@@UNIT_REGEX})\b/    
   end
   
   
   include Comparable
   attr_accessor :scalar, :numerator, :denominator, :signature, :base_scalar, :base_numerator, :base_denominator, :output, :unit_name
@@ -212,10 +211,14 @@
       @numerator = @denominator = UNITY_ARRAY
     when Time:
       @scalar = options[0].to_f
       @numerator = ['<second>']
       @denominator = UNITY_ARRAY
+    when DateTime:
+      @scalar = options[0].ajd
+      @numerator = ['<day>']
+      @denominator = UNITY_ARRAY
     else
       raise ArgumentError, "Invalid Unit Format"
     end
     self.update_base_scalar
     self.replace_temperature
@@ -263,11 +266,12 @@
       return @is_base=false unless x == UNITY || (@@BASE_UNITS.include?((x)))
     end
     return @is_base = true
   end  
   
-  #convert to base SI units
+  # convert to base SI units
+  # results of the conversion are cached so subsequent calls to this will be fast
   def to_base
     return self if self.is_base?
     cached = @@base_unit_cache[self.units] * self.scalar rescue nil
     return cached if cached
     
@@ -300,15 +304,21 @@
     @@base_unit_cache[self.units]=base
     return base * @scalar
   end
   
   # Generate human readable output.
-  # If the name of a unit is passed, the scalar will first be converted to the target unit before output.
+  # If the name of a unit is passed, the unit will first be converted to the target unit before output.
   # some named conversions are available
   #
   #  :ft - outputs in feet and inches (e.g., 6'4")
   #  :lbs - outputs in pounds and ounces (e.g, 8 lbs, 8 oz)
+  #  
+  # You can also pass a standard format string (i.e., '%0.2f')
+  # or a strftime format string.
+  #
+  # output is cached so subsequent calls for the same format will be fast
+  #
   def to_s(target_units=nil)
     out = @output[target_units] rescue nil
     if out
       return out
     else
@@ -332,10 +342,11 @@
       @output = {target_units => out}
       return out
     end    
   end
   
+  # Normally pretty prints the unit, but if you really want to see the guts of it, pass ':dump'
   def inspect(option=nil)
     return super() if option == :dump
     self.to_s
   end
   
@@ -393,15 +404,16 @@
   alias :same? :===
   alias :same_as? :===
   
   # Add two units together.  Result is same units as receiver and scalar and base_scalar are updated appropriately
   # throws an exception if the units are not compatible.
+  # It is possible to add Time objects to units of time
   def +(other)   
     if Unit === other 
       if self =~ other then
-        q = self.zero? ? 1 : (self.scalar / self.base_scalar)
-        Unit.new(:scalar=>(self.base_scalar + other.base_scalar)*q, :numerator=>@numerator, :denominator=>@denominator, :signature => @signature)
+        @q ||= @@cached_units[self.units].scalar / @@cached_units[self.units].base_scalar
+        Unit.new(:scalar=>(self.base_scalar + other.base_scalar)*@q, :numerator=>@numerator, :denominator=>@denominator, :signature => @signature)
       else
          raise ArgumentError,  "Incompatible Units"
       end
     elsif Time === other
       other + self
@@ -414,12 +426,12 @@
   # Subtract two units. Result is same units as receiver and scalar and base_scalar are updated appropriately
   # throws an exception if the units are not compatible.
   def -(other)
     if Unit === other 
       if self =~ other then
-        q = self.zero? ? 1 : (self.scalar / self.base_scalar)
-        Unit.new(:scalar=>(self.base_scalar - other.base_scalar)*q, :numerator=>@numerator, :denominator=>@denominator, :signature=>@signature)
+        @q ||= @@cached_units[self.units].scalar / @@cached_units[self.units].base_scalar
+        Unit.new(:scalar=>(self.base_scalar - other.base_scalar)*@q, :numerator=>@numerator, :denominator=>@denominator, :signature=>@signature)
       else
          raise ArgumentError,  "Incompatible Units"
       end
     elsif Time === other
       other - self
@@ -697,10 +709,14 @@
     Time.at(self)
   end
   alias :time :to_time
   alias :to_i :to_int
   alias :truncate :to_int
+
+  def to_datetime
+    DateTime.new(self.to('d').scalar)
+  end
   
   def round
     Unit.new(@scalar.round, @numerator, @denominator)    
   end
    
@@ -986,11 +1002,11 @@
 
 # Allow date objects to do offsets by a time unit
 # Date.today + U"1 week" => gives today+1 week
 class Date
   alias :unit_date_add :+
-  def +unit
+  def +(unit)
     case unit
     when Unit:
       unit = unit.to('d').round if ['y', 'decade', 'century'].include? unit.units 
       unit_date_add(unit.to('day').scalar)
     when Time: unit_date_add(unit.to_datetime)
@@ -998,21 +1014,26 @@
       unit_date_add(unit)
     end
   end
 
   alias :unit_date_sub :-    
-  def -unit
+  def -(unit)
     case unit
     when Unit: 
       unit = unit.to('d').round if ['y', 'decade', 'century'].include? unit.units 
       unit_date_sub(unit.to('day').scalar)
     when Time: unit_date_sub(unit.to_datetime)
     else
       unit_date_sub(unit)
     end
   end
   
+  def to_unit(other = nil)
+    other ? Unit.new(self).to(other) : Unit.new(self)
+  end
+  alias :unit :to_unit
+  
   def to_time
     Time.local(*ParseDate.parsedate(self.to_s))
   end
   
   alias :units_datetime_inspect :inspect
@@ -1070,11 +1091,10 @@
     end
   end
   
   #needed for compatibility with Rails, which defines a String.from method  
   if self.public_instance_methods.include? 'from'
-    puts 'rails'
     alias :old_from :from
   end 
   
   def from(time_point = ::Time.now)
     return old_from(time_point) if Integer === time_point
@@ -1160,12 +1180,12 @@
     else
       unit_time_at(*args)
     end
   end
   
-  def to_unit(other = "s")
-    other ? Unit.new("#{self.to_f} s").to(other) : Unit.new("#{self.to_f} s")
+  def to_unit(other = nil)
+    other ? Unit.new(self).to(other) : Unit.new(self)
   end
   alias :unit :to_unit
   alias :u :to_unit
   alias :unit_add :+
   
@@ -1184,9 +1204,10 @@
     else
       unit_add(other)
     end
   end
   
+  # usage: Time.in '5 min'
   def self.in(duration)
     Time.now + duration.to_unit
   end
   
   alias :unit_sub :-