class Sequel::SQL::Expression
Base class for all SQL expression objects.
Attributes
All attributes used for equality and hash methods.
Public Instance Methods
Alias of eql?
# File lib/sequel/sql.rb, line 112 def ==(other) eql?(other) end
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 87 def attr_reader(*args) super comparison_attrs.concat(args) end
Returns true if the receiver is the same expression as the the
other
expression.
# File lib/sequel/sql.rb, line 118 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 123 def hash ([self.class] + self.class.comparison_attrs.map{|x| send(x)}).hash end
Copy the ::comparison_attrs into the subclass.
# File lib/sequel/sql.rb, line 93 def inherited(subclass) super subclass.instance_variable_set(:@comparison_attrs, comparison_attrs.dup) 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 129 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 134 def lit self end
Alias of to_s
# File lib/sequel/sql.rb, line 139 def sql_literal(ds) s = '' to_s_append(ds, s) s end