class Sequel::SQL::Expression

Base class for all SQL expression objects.

Attributes

comparison_attrs[R]

All attributes used for equality and hash methods.

Public Class Methods

attr_reader(*args) click to toggle source

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
inherited(subclass) click to toggle source

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

Public Instance Methods

==(other) click to toggle source

Alias of eql?

# File lib/sequel/sql.rb, line 132
def ==(other)
  eql?(other)
end
eql?(other) click to toggle source

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
hash() click to toggle source

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
inspect() click to toggle source

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
lit() click to toggle source

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
sql_literal(ds) click to toggle source

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