Class: Object

Inherits:
BasicObject
Defined in:
lib/range_extd/infinity/infinity.rb

Overview

class Object

Overwrite #<=>() so all its sub-classes can be aware of RangeExtd::Infinity objects (the two constants).

Instance Method Summary collapse

Instance Method Details

#<=>(c) ⇒ Object

Overwrite #<=>(). Then, all its sub-classes can be aware of RangeExtd::Infinity objects (the two constants).

In this definition of #<=>, if self is Comparable (by judging whether it has the method [#<=]), it always returns, unless infinity? and positive? are set accordingly, either -1 or 1, depending which of

RangeExtd::Infinity::(NEGATIVE|POSITIVE)

is compared. If self is not Comparable, the original [#<=>] is called, which should return nil (unless both the object_id agree, eg., nil and nil, in which case 0 is returned).

If you define your own class, which is Comparable, you should define the method “<=>” as follows, as in the standard practice when you redefine a method that exists in a superclass;

Examples:

A method definition of user-defined Comparable class

class MyComparableClass 
  include Comparable
  # alias :cmp_orig :<=> if !self.method_defined?(:cmp_orig)	# if you want
  def <=>(c)
    if c._is_what_i_expect?
      # Write your definition.
    else       # When self does not know what to do with c.
      super c  # to call Object#<=>
    end
  end
end


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# File 'lib/range_extd/infinity/infinity.rb', line 451

def <=>(c)
  return (-(c.send(__method__, self) || return)) if RangeExtd::Infinity.infinity? c
  compare_obj_before_infinity(c)
end

#compare_obj_before_infinity ⇒ Object

No overwriting.



420
 
# File 'lib/range_extd/infinity/infinity.rb', line 420

alias_method :compare_obj_before_infinity, :<=>