Use a scope by default on a Rails has_many relationship - ruby-on-rails-3

Question

Let's say I have the following classes
class SolarSystem < ActiveRecord::Base
has_many :planets
end
class Planet < ActiveRecord::Base
scope :life_supporting, where('distance_from_sun > ?', 5).order('diameter ASC')
end
Planet has a scope life_supporting and SolarSystem has_many :planets. I would like to define my has_many relationship so that when I ask a solar_system for all associated planets, the life_supporting scope is automatically applied. Essentially, I would like solar_system.planets == solar_system.planets.life_supporting.
Requirements
I do not want to change scope :life_supporting in Planet to
default_scope where('distance_from_sun > ?', 5).order('diameter ASC')
I'd also like to prevent duplication by not having to add to SolarSystem
has_many :planets, :conditions => ['distance_from_sun > ?', 5], :order => 'diameter ASC'
Goal
I'd like to have something like
has_many :planets, :with_scope => :life_supporting
Edit: Work Arounds
As #phoet said, it may not be possible to achieve a default scope using ActiveRecord. However, I have found two potential work arounds. Both prevent duplication. The first one, while long, maintains obvious readability and transparency, and the second one is a helper type method who's output is explicit.
class SolarSystem < ActiveRecord::Base
has_many :planets, :conditions => Planet.life_supporting.where_values,
:order => Planet.life_supporting.order_values
end
class Planet < ActiveRecord::Base
scope :life_supporting, where('distance_from_sun > ?', 5).order('diameter ASC')
end
Another solution which is a lot cleaner is to simply add the following method to SolarSystem
def life_supporting_planets
planets.life_supporting
end
and to use solar_system.life_supporting_planets wherever you'd use solar_system.planets.
Neither answers the question so I just put them here as work arounds should anyone else encounter this situation.

Answer 1

In Rails 4, Associations have an optional scope parameter that accepts a lambda that is applied to the Relation (cf. the doc for ActiveRecord::Associations::ClassMethods)
class SolarSystem < ActiveRecord::Base
has_many :planets, -> { life_supporting }
end
class Planet < ActiveRecord::Base
scope :life_supporting, -> { where('distance_from_sun > ?', 5).order('diameter ASC') }
end
In Rails 3, the where_values workaround can sometimes be improved by using where_values_hash that handles better scopes where conditions are defined by multiple where or by a hash (not the case here).
has_many :planets, conditions: Planet.life_supporting.where_values_hash

Answer 2

In Rails 5, the following code works fine...
class Order
scope :paid, -> { where status: %w[paid refunded] }
end
class Store
has_many :paid_orders, -> { paid }, class_name: 'Order'
end

Answer 3

i just had a deep dive into ActiveRecord and it does not look like if this can be achieved with the current implementation of has_many. you can pass a block to :conditions but this is limited to returning a hash of conditions, not any kind of arel stuff.
a really simple and transparent way to achieve what you want (what i think you are trying to do) is to apply the scope at runtime:
# foo.rb
def bars
super.baz
end
this is far from what you are asking for, but it might just work ;)