Class: Object

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

Overview

class Object

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

To activate these features, explicitly do either of the following

require "range_extd/object"
require "range_extd/load_all"

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#<=> or its descendant's
    end
  end
end



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# File 'lib/range_extd/object.rb', line 46

def <=>(c)
  return (-(c.send(__method__, self) || return)) if RangeExtd::Infinity.infinity? c  # Second "return" is essential as c.send() may return nil.
  compare_obj_before_infinity(c)
end

#compare_obj_before_infinity ⇒ Object

Backup of the original method #<=>



15
 
# File 'lib/range_extd/object.rb', line 15

alias_method :compare_obj_before_infinity, :<=>