Class: Unobservable::Event

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

Overview

Minimalistic Event implementation

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Event

Returns a new instance of Event.



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# File 'lib/unobservable.rb', line 155

def initialize
  @handlers = []
end

Instance Attribute Details

#handlers ⇒ Object (readonly)

Returns the value of attribute handlers.



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# File 'lib/unobservable.rb', line 153

def handlers
  @handlers
end

Instance Method Details

#call(*args, &block) ⇒ Object

Pass the specific arguments / block to all of the event handlers. Return true if there was at least 1 event handler; return false otherwise.



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# File 'lib/unobservable.rb', line 205

def call(*args, &block)
  if @handlers.empty?
    return false
  else
    # TODO: Add some form of error-handling
    @handlers.each do |h|
      h.call(*args, &block)
    end

    return true
  end
end

#handler_for(*args, &block) ⇒ Object

There are 3 ways for end-users to provide an event handler:

  1. They can pass an object that has a #call method

  2. They can provide an object and the name of a method to invoke

  3. They can pass in a block

Raises:

  • (ArgumentError) 


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# File 'lib/unobservable.rb', line 164

def handler_for(*args, &block)
  if block
    return block
  elsif args.size == 1
    return args[0]
  elsif args.size == 2
    return args[0].method(args[1])
  end

  raise ArgumentError, "Unable to create an event handler using the given arguments"
end

#register(*args, &block) ⇒ Object

Registers the given event handler so that it will be invoked when the event is raised.



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# File 'lib/unobservable.rb', line 178

def register(*args, &block)
  h = handler_for(*args, &block)
  @handlers << h
  return h
end

#unregister(*args, &block) ⇒ Object

Removes a single instance of the specified event handler from the list of event handlers. Therefore, if you’ve registered the same event handler 3 times, then you will need to unregister it 3 times as well.



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# File 'lib/unobservable.rb', line 189

def unregister(*args, &block)
  h = handler_for(*args, &block)
  index = @handlers.index(h)
  if index
    @handlers.slice!(index)
    return h
  else
    return nil
  end
end