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 110 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 116 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 121 def hash ([self.class] + self.class.comparison_attrs.map{|x| send(x)}).hash end
Attempt to produce a string suitable for eval, such that:
eval(obj.inspect) == obj
# File lib/sequel/extensions/eval_inspect.rb, line 63 def inspect # Assume by default that the object can be recreated by calling # self.class.new with any attr_reader values defined on the class, # in the order they were defined. klass = self.class args = inspect_args.map do |arg| if arg.is_a?(String) && arg =~ /\A\*/ # Special case string arguments starting with *, indicating that # they should return an array to be splatted as the remaining arguments send(arg.sub('*', '')).map{|a| Sequel.eval_inspect(a)}.join(', ') else Sequel.eval_inspect(send(arg)) end end "#{klass}.new(#{args.join(', ')})" end
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