Base class for all SQL expression objects.
All attributes used for equality and hash methods.
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 107 def attr_reader(*args) super comparison_attrs.concat(args) end
Copy the ::comparison_attrs into the subclass.
# File lib/sequel/sql.rb, line 113 def inherited(subclass) super subclass.instance_variable_set(:@comparison_attrs, comparison_attrs.dup) end
Alias of eql?
# File lib/sequel/sql.rb, line 132 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 138 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 143 def hash ([self.class] + self.class.comparison_attrs.map{|x| send(x)}).hash end
Show the class name and instance variables for the object.
# File lib/sequel/sql.rb, line 148 def inspect "#<#{self.class} #{instance_variables.map{|iv| "#{iv}=>#{instance_variable_get(iv).inspect}"}.join(', ')}>" end
Returns self
, because SQL::Expression
already
acts like LiteralString
.
# File lib/sequel/sql.rb, line 153 def lit Sequel::Deprecation.deprecate("Sequel::SQL::Expression#lit", "This method returns self, so just use the receiver") self end
Alias of to_s
# File lib/sequel/sql.rb, line 159 def sql_literal(ds) Sequel::Deprecation.deprecate("Sequel::SQL::Expression#sql_literal", "Call Sequel::Dataset#literal with the expression instead") s = String.new to_s_append(ds, s) s end