class-cattr gem provides simple way to set and get class attributes.
to install
gem install class-cattr
or in Gemfile
gem 'class-cattr'
and to use
require 'class-cattr'
- require 'class-cattr'
- define class attributes as
cattr :name, default: value, class: true|fase, instance: true|false - get them via
cattr.name(or via class and instance method if provided)
class AppModel
# define :admin_path class attrbiute with class and instance methodss
cattr :admin_path,
# defaults value will be calculated on read, if proc provided
default: proc { '/admin/%s' % to_s.tableize },
# create class setter and getter
class: true,
# create instance setter and getter
instance: true
# :icon, default value is nil
cattr :icon, 'undefined.png'
end
class User < AppModel
cattr.icon = 'user.png'
end
class Product < AppModel
end
###
User.cattr.admin_path # '/admin/people' (available allways)
User.admin_path # '/admin/people' (from class: true)
@user.cattr.admin_path # '/admin/people' (available allways)
@user.admin_path # '/admin/people' (from instance: true)
User.cattr.icon # 'user.png'
User.icon # NoMethodErorr
@user.cattr.icon # 'user.png'
@user.icon # NoMethodErorr
Product.cattr.icon # 'undefined.png'
Product.icon # NoMethodErorr
@product.cattr.icon # 'undefined.png'
@product.icon # NoMethodErorrTips
class User
cattr :icon, 'undefined.png'
# can ve defined as
cattr.icon = 'undefined.png'
# but in this fashion you can't define class and instance setters and getters
# this all all the same
catr.time_now = proc { Time.now }
catr(:time_now) { Time.now }
catr :time_now, default: proc { Time.now }
# you can define argument withut equal sign
self.admin_path 'foo'
# same as
self.admin_path = 'foo'
end
# it is advice to define cattr with
cattr :name, opts
# and use via
Klass.cattr.name
@klass.cattr.nameQ: Why did you create this when Rails provides class_attribute ?
A: There is a small but nimble Ruby community that uses Ruby and outside the Rails eco-system.
Q: Why did you not use some and improve one of the existing similar libs?
A: I like clean interface without base class pollution, approach I did not find anywhre.
This gem only adds cattr methods to class and instance.
Optionaly, you can polute only class methods, you can pollute instance only methods, or both.
none
After checking out the repo, run bundle install to install dependencies. Then, run rspec to run the tests.
Bug reports and pull requests are welcome on GitHub at https://github.com/dux/class-cattr. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.
The gem is available as open source under the terms of the MIT License.