ActiveSupport

ACTIVESUPPORT

Sunday, September 12, 2010

WHOAMI


HOW WE WRITE MODULES


module M
def self.included(base)
base.extend, ClassMethods
base.send(:include, InstanceMethods)
scope :disabled, where(:disabled => true)
end

module ClassMethods
...
end

module InstanceMethods
...
end
end

previously wrote

HOW WE WRITE MODULES


ACTIVESUPPORT::CONCERN


module M
extend ActiveSupport::Concern

included do
scope :disabled, where(:disabled => true)
end

module ClassMethods
...
end

module InstanceMethods
...
end
end

Why use it?


...it handles dependencies to other
modules!


module Bar
include Foo

included do
self.method_injected_by_foo
end
end

class Host
include Bar
end


ActiveSupport::Concern in the Wild


module Mongoid #:nodoc
module Indexes #:nodoc

included do
cattr_accessor :index_options
self.index_options = {}
end

module ClassMethods #:nodoc

# Send the actual index creation comments to the MongoDB driver
def create_indexes
return unless index_options
current_collection = self._collection || set_collection
index_options.each do |name, options|
current_collection.create_index(name, options)
end
end
...
end
end
end


PLUGGABLE JSON BACKENDS


#to_json calls ActiveSupport::JSON.encode()


Rails used to only have YAML-based JSON support


ActiveSupport::JSON.backend = 'Yajl'


YAJL BENCHMARKS
Yajl::Encoder#encode: 3.59s
JSON#to_json: 6.2s
ActiveSupport::JSON.encode: 45.58s

Yajl::Parser#parse: 4.54s
JSON.parse: 5.47s
ActiveSupport::JSON.decode: 64.42s


PRESENCE


BEFORE

name = params[:name] unless params[:name].blank?


NOW

name = params[:name] if params[: name].present?


BEFORE

state = params[:state] unless params[:state].blank?
country = params[:country] unless params[:country].blank?
region = state || country || 'US'


NOW

region = params[:state].presence || params[:country].presence || 'US'


ARRAY#UNIQ_BY


[1, 2, 3, 4].uniq_by(&:odd?)
#=> [1, 2]


CLASS_ATTRIBUTE


Declare one or more class-level attribute
whose value is inheritable and over-writable by
subclasses and instances


>> Base.setting = "foo" => "foo"
>> Subclass.setting => "foo"
>> Subclass.setting = "bar" => "bar"
>> Base.setting => "foo"


QUESTIONS?


ActiveSupport

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