Module: AttrComparable::ClassMethods

Defined in:
lib/attr_comparable.rb

Instance Method Summary collapse

Instance Method Details

#attr_compare(*attributes) ⇒ Object 



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# File 'lib/attr_comparable.rb', line 33

def attr_compare(*attributes)
  attr_exprs = (attributes.flatten).map do |attribute|
    '(' + compare_with_nil_code("self.#{attribute}", "rhs.#{attribute}").strip + ')'
  end

  class_eval "    def <=>(rhs)\n      unless rhs.nil?\n        \#{ attr_exprs.join(\".nonzero? || \") }\n      end\n    end\n  EOS\nend\n"

#compare_with_nil_code(left, right) ⇒ Object

like <=> but handles nil values returns the code in string form to be eval’d



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# File 'lib/attr_comparable.rb', line 14

def compare_with_nil_code(left, right)
  "    if \#{ left }.nil?\n      if \#{ right }.nil?\n        0\n      else\n        -1\n      end\n    elsif \#{ right }.nil?\n      1\n    else\n      if (cmp_result = (\#{ left } <=> \#{ right })).nil?\n        return nil\n      end\n      cmp_result\n    end\n  EOS\nend\n"