class Sequel::SQL::Expression

  1. lib/sequel/sql.rb
Superclass: Object

Base class for all SQL expression objects.


Public Class

  1. attr_reader
  2. comparison_attrs
  3. inherited

Public Instance

  1. ==
  2. clone
  3. eql?
  4. hash
  5. inspect

Public Instance Aliases

dup -> clone


comparison_attrs [R]

All attributes used for equality and hash methods.

Public Class methods

attr_reader (*args)

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.

[show source]
   # File lib/sequel/sql.rb
91 def attr_reader(*args)
92   super
93   comparison_attrs.concat(args)
94 end
inherited (subclass)

Copy the comparison_attrs into the subclass.

[show source]
    # File lib/sequel/sql.rb
 97 def inherited(subclass)
 98   super
 99   subclass.instance_variable_set(:@comparison_attrs, comparison_attrs.dup)
100 end

Public Instance methods

== (other)

Alias of eql?

[show source]
    # File lib/sequel/sql.rb
124 def ==(other)
125   eql?(other)
126 end
clone ()

Make clone/dup return self, since Expression objects are supposed to be frozen value objects

[show source]
    # File lib/sequel/sql.rb
118 def clone
119   self
120 end
eql? (other)

Returns true if the receiver is the same expression as the the other expression.

[show source]
    # File lib/sequel/sql.rb
130 def eql?(other)
131   other.is_a?(self.class) && !self.class.comparison_attrs.find{|a| public_send(a) != other.public_send(a)}
132 end
hash ()

Make sure that the hash value is the same if the attributes are the same.

[show source]
    # File lib/sequel/sql.rb
135 def hash
136   ([self.class] +{|x| public_send(x)}).hash
137 end
inspect ()

Show the class name and instance variables for the object.

[show source]
    # File lib/sequel/sql.rb
140 def inspect
141   "#<#{self.class} #{{|iv| "#{iv}=>#{instance_variable_get(iv).inspect}"}.join(', ')}>"
142 end