module Innate::StateAccessor
Simplify accessing Thread.current variables.
Example:
class Foo include Innate::StateAccessor state_accessor :session def calculate session[:num1] + session[:num2] end end
Foo#calculate can now be called from anywhere in your application and it will have direct access to the session in the current request/response cycle in a thread-safe way without the need to explicitly pass the session along.
Public Class Methods
Iterate over the names and yield accordingly. names are either objects responding to to_sym or hashes.
It's only used within this module to make the code readable.
Used below.
# File lib/innate/state/accessor.rb, line 29 def self.each(*names) names.each do |name| if name.respond_to?(:to_hash) name.to_hash.each do |key, meth| yield(key.to_sym, meth.to_sym) end else key = meth = name.to_sym yield(key, meth) end end end
Public Instance Methods
Combined #state_writer and
state_reader. initializer
is a block that may be given and its
result will be the new value in case the method created by #state_reader was never
called before and the value wasn't set before.
Example:
state_accessor(:session) state_accessor(:user){ session[:user] }
# File lib/innate/state/accessor.rb, line 52 def state_accessor(*names, &initializer) state_writer(*names) state_reader(*names, &initializer) end
Reader accessor for Thread.current
Example:
class Foo include Innate::StateAccessor state_reader(:session) state_reader(:random){ rand(100_000) } def calculate val1 = session[:num1] + session[:num2] + random val2 = session[:num1] + session[:num2] + random val1 == val2 # => true end end
NOTE:
If given +initializer+, there will be some performance impact since we cannot use class_eval and have to use define_method instead, we also have to check every time whether the initializer was executed already. In 1.8.x the overhead of define_method is 3x that of class_eval/def In 1.9.1 the overhead of define_method is 1.5x that of class_eval/def This may only be an issue for readers that are called a lot of times.
# File lib/innate/state/accessor.rb, line 114 def state_reader(*names, &initializer) StateAccessor.each(*names) do |key, meth| if initializer define_method(meth) do unless Thread.current.key?(key) Thread.current[key] = instance_eval(&initializer) else Thread.current[key] end end else class_eval("def %s; Thread.current[%p]; end" % [meth, key]) end end end
Writer accessor to Thread.current=
Example: class Foo include Innate::StateAccessor state_writer(:result) def calculate self.result = 42 end end class Bar include Innate::StateAccessor state_reader(:result) def calculcate result * result end end Foo.new.calculate # => 42 Bar.new.calculate # => 1764
# File lib/innate/state/accessor.rb, line 82 def state_writer(*names) StateAccessor.each(*names) do |key, meth| class_eval("def %s=(obj) Thread.current[%p] = obj; end" % [meth, key]) end end