Inheritance

Flows, Operations, and States all support inheritance of class definitions.

class ParentState < ApplicationState
  argument :foo
end

class ChildState < ParentState
  argument :bar
end

class ChildFlow < ApplicationFlow; end
ChildFlow.trigger(bar: :bar) # => ArgumentError (Missing argument: foo)

A common pattern in Flow is to use inheritance to DRY and conceptually related flows.

Take for example the case of Calculation and Recalculation

class CalculateFooFlow < ApplicationFlow
  operations ClearOldFooCalculations, CaclulcateFoo, EmailFooReport
end

class CalculateFooState < ApplicationState
  def foos
    Foo.where(calculated_at: nil)
  end
end

# =================

class RecalculateFooFlow < CalculateFooFlow; end
class RecalculateFooState < ApplicationState
  def foos
    Foo.all
  end
end

There communicates that there is no difference between the Flows other than their States!