Module: Concurrent::Concern::Dereferenceable
- Included in:
- Obligation, MVar, TimerTask
- Defined in:
- lib/concurrent-ruby/concurrent/concern/dereferenceable.rb
Overview
Object references in Ruby are mutable. This can lead to serious problems when
the #value
of a concurrent object is a mutable reference. Which is always the
case unless the value is a Fixnum
, Symbol
, or similar "primitive" data type.
Most classes in this library that expose a #value
getter method do so using the
Dereferenceable
mixin module.
Copy Options
Object references in Ruby are mutable. This can lead to serious
problems when the #value of an object is a mutable reference. Which
is always the case unless the value is a Fixnum
, Symbol
, or similar
"primitive" data type. Each instance can be configured with a few
options that can help protect the program from potentially dangerous
operations. Each of these options can be optionally set when the object
instance is created:
:dup_on_deref
When true the object will call the#dup
method on thevalue
object every time the#value
method is called (default: false):freeze_on_deref
When true the object will call the#freeze
method on thevalue
object every time the#value
method is called (default: false):copy_on_deref
When given aProc
object theProc
will be run every time the#value
method is called. TheProc
will be given the currentvalue
as its only argument and the result returned by the block will be the return value of the#value
call. Whennil
this option will be ignored (default: nil)
When multiple deref options are set the order of operations is strictly defined. The order of deref operations is:
:copy_on_deref
:dup_on_deref
:freeze_on_deref
Because of this ordering there is no need to #freeze
an object created by a
provided :copy_on_deref
block. Simply set :freeze_on_deref
to true
.
Setting both :dup_on_deref
to true
and :freeze_on_deref
to true
is
as close to the behavior of a "pure" functional language (like Erlang, Clojure,
or Haskell) as we are likely to get in Ruby.
Instance Method Summary collapse
-
#value ⇒ Object
(also: #deref)
Return the value this object represents after applying the options specified by the
#set_deref_options
method.
Instance Method Details
#value ⇒ Object Also known as: deref
Return the value this object represents after applying the options specified
by the #set_deref_options
method.
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# File 'lib/concurrent-ruby/concurrent/concern/dereferenceable.rb', line 21 def value synchronize { (@value) } end |