Class: Object

Inherits:
BasicObject
Defined in:
lib/active_support_ext/object/duplicable.rb,
lib/active_support_ext/object/deep_dup.rb

Overview

– Most objects are cloneable, but not all. For example you can’t dup methods:

method(:puts).dup # => TypeError: allocator undefined for Method

Classes may signal their instances are not duplicable removing dup/clone or raising exceptions from them. So, to dup an arbitrary object you normally use an optimistic approach and are ready to catch an exception, say:

arbitrary_object.dup rescue object

Rails dups objects in a few critical spots where they are not that arbitrary. That rescue is very expensive (like 40 times slower than a predicate), and it is often triggered.

That’s why we hardcode the following cases and check duplicable? instead of using that rescue idiom. ++

Instance Method Summary collapse

Instance Method Details

#deep_dup ⇒ Object

Returns a deep copy of object if it’s duplicable. If it’s not duplicable, returns self.

object = Object.new
dup    = object.deep_dup
dup.instance_variable_set(:@a, 1)

object.instance_variable_defined?(:@a) # => false
dup.instance_variable_defined?(:@a)    # => true



18
19
20
 
# File 'lib/active_support_ext/object/deep_dup.rb', line 18

def deep_dup
  duplicable? ? dup : self
end

#duplicable? ⇒ Boolean

Can you safely dup this object?

False for method objects; true otherwise.

Returns:

  • (Boolean) 


29
30
31
 
# File 'lib/active_support_ext/object/duplicable.rb', line 29

def duplicable?
  true
end