Class: Sequel::SQL::Expression

Inherits:
Object
  • Object
show all
Defined in:
lib/sequel/sql.rb

Overview

Base class for all SQL expression objects.

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.attr_reader(*args) ⇒ Object

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.



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# File 'lib/sequel/sql.rb', line 68

def self.attr_reader(*args)
  super
  comparison_attrs.concat args
end

.comparison_attrs ⇒ Object

All attributes used for equality and hash methods.



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# File 'lib/sequel/sql.rb', line 74

def self.comparison_attrs
  @comparison_attrs ||= self == Expression ? [] : superclass.comparison_attrs.clone
end

Instance Method Details

#==(other) ⇒ Object

Alias of eql?



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# File 'lib/sequel/sql.rb', line 87

def ==(other)
  eql?(other)
end

#eql?(other) ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/sql.rb', line 93

def eql?(other)
  other.is_a?(self.class) && !self.class.comparison_attrs.find{|a| send(a) != other.send(a)}
end

#hash ⇒ Object

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



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# File 'lib/sequel/sql.rb', line 98

def hash
  ([self.class] + self.class.comparison_attrs.map{|x| send(x)}).hash
end

#inspect ⇒ Object

Show the class name and instance variables for the object, necessary for correct operation on ruby 1.9.2.



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# File 'lib/sequel/sql.rb', line 104

def inspect
  "#<#{self.class} #{instance_variables.map{|iv| "#{iv}=>#{instance_variable_get(iv).inspect}"}.join(', ')}>"
end

#lit ⇒ Object

Returns self, because SQL::Expression already acts like LiteralString.



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# File 'lib/sequel/sql.rb', line 109

def lit
  self
end

#sql_literal(ds) ⇒ Object

Alias of to_s



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# File 'lib/sequel/sql.rb', line 114

def sql_literal(ds)
  to_s(ds)
end