Assigning attributes can nil them out

[tfausak]

This is distressing, to say the least:

class Interaction < ActiveInteraction::Base
  boolean :a
  def execute; a = a end
end
p Interaction.run!(a: true)
# => nil

[tfausak]

Only happens the first time:

class Interaction < ActiveInteraction::Base
  boolean :a
  def execute
    a = false
    a = a
  end
end
p Interaction.run!(a: true)
# => false

[tfausak]

Getting more confused:

class Interaction < ActiveInteraction::Base
  boolean :a
  def execute
    b = a
    a = b
  end
end
p Interaction.run!(a: true)
# => true

[tfausak]

Adding self. makes it work:

class Interaction < ActiveInteraction::Base
  boolean :a
  def execute; a = self.a end
end
p Interaction.run!(a: true)
# => true

[tfausak]

Turns out this is not a bug against ActiveInteraction — it's just weird Ruby behavior!

class Klass
  def initialize;   @thing = 'swamp' end
  def thing;        @thing end
  def thing=(other) @thing = other end
  def test1;        thing = thing end
  def test2;        self.thing = thing end
  def test3;        thing = self.thing end
end
klass = Klass.new
p klass.test1 # => nil
p klass.test2 # => "swamp"
p klass.test3 # => "swamp"

[tfausak]

https://www.destroyallsoftware.com/talks/wat