Condensable

In chemistry, condensation is the process of vapour or gas to become a liquid. But, this is no chemistry things. Here, condensable is describing a condition of a class that allow to make itself respond to getter and setter routines when they are not (yet) defined.

Condensation works well with Assignbot!

Installation

Add this line to your application's Gemfile:

gem 'condensable'

And then execute:

$ bundle

Or install it yourself as:

$ gem install condensable

Usage

Simple enough, just include Condensable into your class and you are set.

class OrderParams
  include Condensable
end

And, you can use your condensable instance as follow:

order = OrderParams.new
order.order_id = 12
order.customer = "Adam Pahlevi Baihaqi"

Notice that both order_id and customer have not yet been defined, but a condensable class would automatically define that on-demand.

Creating on-the-fly condensable class

You don't need to define a class, you can generate them on-demand:

order = Condensable.new.new
order.order_id = 123

First .new will create a class on-the-fly for you. The second .new actually initialize the class.

You can also pass in block, and define what a usual class could be defined:

order = Condensable.new do
  def full_name
    "#{first_name} #{last_name}"
  end
end.new

order.first_name = 'Adam'
order.last_name = 'Pahlevi'
order.full_name == 'Adam Pahlevi' # true

For more, please have a look at our spec to demonstrate its power.

Specifying default condensation behaviour

By default, when a getter is not available, a condensable instance will return nil:

order.shipping_address == nil # true

To alter the default behaviour, specify condensable default in your class, like below:

class OrderParams
  include Condensable

  condensable default: "not-available"
end

Therefore, when invoked:

order.shipping_address

It will returns not-available.

There are 4 condensation behaviours:

1. Returning nil (condensable default: nil)
2. Returning string (condensable default: "some string")
3. Executing a method, by always passing a symbol (condensable default: :execute_method)
4. Raising an error (condensable default: :raise_error)

For more details, please see the spec which demonstrates the all four.

Iterating condensed variables

To get to know what are all the condensed variables, use:

order.condensed_variables

To get to know all of condensed values, use:

order.condensed_values

Iterating both:

order.each do |condensed_var, condensed_value|
  puts "#{condensed_var}: #{condensed_value}"
end

Checking whether an attribute is a result of condensation

order.is_condensed?(:order_id)          # ==> true
order.is_condensed?(:shipping_address)  # ==> false

License

The gem is proudly available as open source under the terms of the MIT License.