lib/constant_cache/core_ext.rb spec/examples/constant_cache/core_ext_spec.rb @@ -1,2 +1,3 @@ pkg coverage +doc .gitignore @@ -1,3 +1,9 @@ +== 0.0.2 2009-04-?? + +* Enhancements + * Better documentation + * Modify String class directly instead of using a mix-in + == 0.0.1 2008-04-08 * 1 major enhancement: HISTORY @@ -1,5 +1,4 @@ -ConstantCache -=============== += Constant Cache When your database has tables that store lookup data, there is a tendency to provide those values as constants in the model. If you have an @@ -21,21 +20,19 @@ The constants are stored as integer values and need to match up exactly with the data that's in the table (not necessarily a bad thing), but this solution forces you to write code like this: -Account.new(:username => 'preagan', :status => AccountStatus.find(AccountStatus::PENDING)) + Account.new(:username => 'preagan', :status => AccountStatus.find(AccountStatus::PENDING)) This requires multiple calls to find and obfuscates the code a bit. Since classes in Ruby are executable code, we can cache the objects from the database at runtime and use them in your application. -Installation -============ +== Installation This code is packaged as a gem, so simply use the `gem` command to install: gem install constant_cache -Example -======= +== Example "Out of the box," the constant_cache gem assumes that you want to use the 'name' column to generate constants from a column called 'name' in your database table. Assuming this schema: @@ -72,4 +69,9 @@ well: caches_constants :limit => 16 end -Copyright (c) 2007 Patrick Reagan of Viget Labs (patrick.reagan@viget.com), released under the MIT license +== Acknowlegements + +Thanks to Dave Thomas for inspiring me to write this during his Metaprogramming talk at a Rails Edge +conference in early 2007. + +Copyright (c) 2007 Patrick Reagan of Viget Labs (mailto:patrick.reagan@viget.com), released under the MIT license README @@ -26,8 +26,7 @@ spec = Gem::Specification.new do |s| s.add_dependency('activesupport', '>= 2.0.2') s.require_path = 'lib' - s.autorequire = GEM - s.files = %w(MIT-LICENSE README Rakefile HISTORY) + Dir.glob("{lib,spec}/**/*") + s.files = %w(MIT-LICENSE README Rakefile HISTORY) + Dir.glob("{lib,spec}/**/*") end Rake::GemPackageTask.new(spec) do |pkg| Rakefile @@ -1,6 +1,5 @@ -require 'constant_cache/format' +require 'constant_cache/core_ext' require 'constant_cache/cache_methods' -String.send(:include, ConstantCache::Format) ActiveRecord::Base.send(:extend, ConstantCache::CacheMethods::ClassMethods) ActiveRecord::Base.send(:include, ConstantCache::CacheMethods::InstanceMethods) \ No newline at end of file lib/constant_cache.rb @@ -1,15 +1,48 @@ module ConstantCache + + CHARACTER_LIMIT = 64 + # + # Generated constant conflicts with an existing constant + # class DuplicateConstantError < StandardError; end - class InvalidLimitError < StandardError; end + class InvalidLimitError < StandardError #:nodoc: + end - module CacheMethods + module CacheMethods #:nodoc: module ClassMethods + + # + # The caches_constants method is the core of the functionality behind this mix-in. It provides + # a simple interface to cache the data in the corresponding table as constants on the model: + # + # class Status + # caches_constants + # end + # + # It makes certain assumptions about your schema: the constant created is based off of a <tt>name</tt> + # column in the database and long names are truncated to ConstantCache::CHARACTER_LIMIT characters before + # being set as constants. If there is a 'Pending' status in the database, you will now have a + # Status::PENDING constant that points to an instance of ActiveRecord. + # + # Beyond the basics, some configuration is allowed. You can change both the column that is used to generate + # the constant and the truncation length: + # + # class State + # caches_constants :key => :abbreviation, :limit => 2 + # end + # + # This will use the <tt>abbreviation</tt> column to generate constants and will truncate constant names to 2 + # characters at the maximum. + # + # Note: In the event that a generated constant conflicts with an existing constant, a + # ConstantCache::DuplicateConstantError is raised. + # def caches_constants(additional_options = {}) cattr_accessor :cache_options - self.cache_options = {:key => :name, :limit => 64}.merge(additional_options) + self.cache_options = {:key => :name, :limit => ConstantCache::CHARACTER_LIMIT}.merge(additional_options) raise ConstantCache::InvalidLimitError, "Limit of #{self.cache_options[:limit]} is invalid" if self.cache_options[:limit] < 1 find(:all).each {|model| model.set_instance_as_constant } @@ -18,16 +51,23 @@ module ConstantCache module InstanceMethods - def constant_name + def constant_name #:nodoc: constant_name = self.send(self.class.cache_options[:key].to_sym).constant_name constant_name = constant_name[0, self.class.cache_options[:limit]] unless constant_name.blank? constant_name end + private :constant_name + # + # Create a constant on the class that pointing to an instance + # def set_instance_as_constant const = constant_name if !const.blank? - raise ConstantCache::DuplicateConstantError, "Constant #{self.class.to_s}::#{const} has already been defined" if self.class.const_defined?(const) + if self.class.const_defined?(const) + message = "Constant #{self.class.to_s}::#{const} has already been defined" + raise ConstantCache::DuplicateConstantError, message + end self.class.const_set(const, self) if !const.blank? end end lib/constant_cache/cache_methods.rb @@ -1,9 +1,9 @@ module ConstantCache - module VERSION + module VERSION #:nodoc: MAJOR = 0 MINOR = 0 - TINY = 1 + TINY = 2 STRING = [MAJOR, MINOR, TINY].join('.') end lib/constant_cache/version.rb @@ -5,8 +5,6 @@ require 'mocha' require 'activesupport' require 'activerecord' - - lib_dir = File.join(File.dirname(__FILE__), %w(.. lib constant_cache)) Dir.glob("#{lib_dir}/*.rb").each {|file| require file } @@ -27,7 +25,6 @@ end Spec::Runner.configuration.mock_with :mocha Spec::Runner.configuration.include ConstantCache::SpecHelper -String.send(:include, ConstantCache::Format) ActiveRecord::Base.send(:include, ConstantCache::CacheMethods::InstanceMethods) ActiveRecord::Base.send(:extend, ConstantCache::CacheMethods::ClassMethods) spec/spec_helper.rb lib/constant_cache/format.rb spec/examples/constant_cache/format_spec.rb test_helper.rb 763901ee6af5f0c5d64d7ec35e41c6a0825ab9ba Patrick Reagan patrick.reagan@viget.com http://github.com/vigetlabs/constant_cache/commit/da8ecd91d84250328d72035562525d61e1c1ea5c da8ecd91d84250328d72035562525d61e1c1ea5c 2008-04-14T22:41:42-07:00 2008-04-14T22:41:42-07:00 Improved documentation Add String#constant_name directly d3fa4929fd1d1aa825084555bd043e71e5483e83 Patrick Reagan patrick.reagan@viget.com