Class: RubyEventStore::Projection

Inherits:
Object
  • Object
show all
Defined in:
lib/ruby_event_store/projection.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(initial_state) ⇒ Projection

Returns a new instance of Projection.



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# File 'lib/ruby_event_store/projection.rb', line 14

def initialize(initial_state)
  @handlers = {}
  @init = -> { initial_state }
end

Class Method Details

.init(initial_state = nil) ⇒ Object 



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# File 'lib/ruby_event_store/projection.rb', line 10

def self.init(initial_state = nil)
  new(initial_state)
end

Instance Method Details

#call(scope) ⇒ Object 



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# File 'lib/ruby_event_store/projection.rb', line 31

def call(scope)
  return initial_state if handled_events.empty?

  scope.of_type(handled_events).reduce(initial_state, &method(:transition))
end

#on(*event_klasses, &block) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/ruby_event_store/projection.rb', line 19

def on(*event_klasses, &block)
  raise(ArgumentError, "No handler block given") unless block_given?

  event_klasses.each do |event_klass|
    name = event_klass.to_s
    raise(ArgumentError, "Anonymous class is missing name") if name.start_with? ANONYMOUS_CLASS

    @handlers[name] = ->(state, event) { block.call(state, event) }
  end
  self
end