In my program I am using a state machine, and have numerous convenience methods. I am currently creating a long list of "?" methods in the model.
def purchase_ready?
self.current_state == 'purchase_ready'
end
def completed?
self.current_state == 'completed'
end
def region_prepared?
self.current_state == 'region_prepared'
end
What's the metaprogramming way to do this?
...and here's an answer!
Thanks to this blog: http://rohitrox.github.io/2013/07/02/ruby-dynamic-methods/
[:purchase_ready, :completed, :region_prepared].each do |method|
define_method "#{method}?" do
self.current_state == "#{method}"
end
end
The lazy way is to use BasicObject#method_missing:
class State
def initialize state
@state = state
end
def method_missing name, *args
case name
when :purchase_ready, :completed, :region_prepared
@state == name
else
super
end
end
end
state = State.new(:purchase_ready)
state.purchase_ready
#=> true
state.completed
#=> false
state.region_prepared
#=> false
state.purchase_not_ready
#-> NoMethodError: undefined method `purchase_not_ready' for
# #<State:0x007f9dfb9674b8 @state=:purchase_ready>
