Class: Unit::SimpleUnit

Inherits:
Object
  • Object
show all
Includes:
Comparable
Defined in:
lib/unitmanager/simple_unit.rb

Overview

Implementation of what is called ‘simple unit of measure’. This is a linear unit which is optionally based on some other simple unit with linear coefficient. Example: :cm is based on :mm with coefficient equal 10. In other words X cm = 10 * Y mm.

Constant Summary collapse

@@EMPTY_UNIT = 
SimpleUnit.new()

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Comparable

#compatible?, #contains?

Constructor Details

#initialize(args = {}) ⇒ SimpleUnit

Returns a new instance of SimpleUnit.



39
40
41
42
43
44
 
# File 'lib/unitmanager/simple_unit.rb', line 39

def initialize (args = {})
  @unit = args[:unit]
  @based_on = args[:based_on] || nil
  @coefficient = args[:coefficient] || 1
  @unit_sym = {:dividends => [@unit], :divisors => [], :string => @unit.to_s}
end

Instance Attribute Details

#based_on ⇒ Object (readonly)

Returns the value of attribute based_on.



35
36
37
 
# File 'lib/unitmanager/simple_unit.rb', line 35

def based_on
  @based_on
end

#coefficient ⇒ Object (readonly)

Returns the value of attribute coefficient.



35
36
37
 
# File 'lib/unitmanager/simple_unit.rb', line 35

def coefficient
  @coefficient
end

#unit ⇒ Object (readonly)

Returns the value of attribute unit.



35
36
37
 
# File 'lib/unitmanager/simple_unit.rb', line 35

def unit
  @unit
end

Instance Method Details

#==(other) ⇒ Object

Two Simple units are equal if they have same symbol, based on the same unit with the same coefficient



72
73
74
75
76
77
 
# File 'lib/unitmanager/simple_unit.rb', line 72

def ==(other)
  return false if other == nil
  return false unless other.kind_of?(self.class)
  
  unit == other.unit && based_on == other.based_on && coefficient == other.coefficient     
end

#[](symbol) ⇒ Object

This method allows to retrieve symbolic portions of the unit definition. Supported values are: :dividends - returns an array of symbols representing dividend part of 

unit definition.

:string - string representation of the unit of measure.



88
89
90
 
# File 'lib/unitmanager/simple_unit.rb', line 88

def [] (symbol)
  @unit_sym[symbol]
end

#dividend ⇒ Object 



62
63
64
 
# File 'lib/unitmanager/simple_unit.rb', line 62

def dividend
  @unit
end

#divisor ⇒ Object 



66
67
68
 
# File 'lib/unitmanager/simple_unit.rb', line 66

def divisor
  @@EMPTY_UNIT
end

#eql?(other) ⇒ Boolean

Returns:

  • (Boolean) 


79
80
81
 
# File 'lib/unitmanager/simple_unit.rb', line 79

def eql?(other)
  self == other
end

#from_base(value) ⇒ Object 



51
52
53
54
 
# File 'lib/unitmanager/simple_unit.rb', line 51

def from_base(value)
  value = @based_on.from_base(value) if derived?
  value /= @coefficient
end

#h_base ⇒ Object

Returns unit representing hierarchy base for the given unit. The Hierarchy is the “based on” chain.



58
59
60
 
# File 'lib/unitmanager/simple_unit.rb', line 58

def h_base
  derived? ? @based_on.h_base : self
end

#to_base(value) ⇒ Object 



46
47
48
49
 
# File 'lib/unitmanager/simple_unit.rb', line 46

def to_base(value)
  value = @based_on.to_base(value) if derived?
  value *= @coefficient
end