Base class for all SQL expression objects.
Expression objects are assumed to be value objects, where their attribute values can't change after assignment. In order to make it easy to define equality and hash methods, subclass instances assume that the only values that affect the results of such methods are the values of the object's attributes.
# File lib/sequel/sql.rb, line 76 def attr_reader(*args) super comparison_attrs.concat(args) end
Copy the comparison_attrs into the subclass.
# File lib/sequel/sql.rb, line 82 def inherited(subclass) super subclass.instance_variable_set(:@comparison_attrs, comparison_attrs.dup) end
Alias of eql?
# File lib/sequel/sql.rb, line 101 def ==(other) eql?(other) end
Returns true if the receiver is the same expression as the the other expression.
# File lib/sequel/sql.rb, line 107 def eql?(other) other.is_a?(self.class) && !self.class.comparison_attrs.find{|a| send(a) != other.send(a)} end
Make sure that the hash value is the same if the attributes are the same.
# File lib/sequel/sql.rb, line 112 def hash ([self.class] + self.class.comparison_attrs.map{|x| send(x)}).hash end
Show the class name and instance variables for the object, necessary for correct operation on ruby 1.9.2.
# File lib/sequel/sql.rb, line 118 def inspect "#<#{self.class} #{instance_variables.map{|iv| "#{iv}=>#{instance_variable_get(iv).inspect}"}.join(', ')}>" end
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