Class: Roby::Promise::Null

Inherits:
Object show all
Defined in:
lib/roby/promise.rb

Overview

A null object for Roby::Promise

Instance Method Summary collapse

Constructor Details

#initialize(value = nil) ⇒ Null

Returns a new instance of Null.



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# File 'lib/roby/promise.rb', line 333

def initialize(value = nil)
    @creation_time = Time.now
    @value = value
end

Instance Method Details

#add_observer(&block) ⇒ Object 



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# File 'lib/roby/promise.rb', line 406

def add_observer(&block)
    block.call(@creation_time, value, nil)
end

#before ⇒ Object

Raises:

  • (NullPromise) 


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# File 'lib/roby/promise.rb', line 346

def before(*)
    raise NullPromise, "attempting to add a step on a null promise"
end

#complete? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/roby/promise.rb', line 378

def complete?
    true
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/roby/promise.rb', line 342

def empty?
    true
end

#execute ⇒ Object 



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# File 'lib/roby/promise.rb', line 366

def execute
    self
end

#fail ⇒ Object

Raises:

  • (NullPromise) 


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# File 'lib/roby/promise.rb', line 362

def fail(*)
    raise NullPromise, "a null promise cannot fail"
end

#fulfilled? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/roby/promise.rb', line 382

def fulfilled?
    true
end

#null? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/roby/promise.rb', line 338

def null?
    true
end

#on_error ⇒ Object

Raises:

  • (NullPromise) 


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# File 'lib/roby/promise.rb', line 354

def on_error(*)
    raise NullPromise, "attempting to add a step on a null promise"
end

#on_success ⇒ Object

Raises:

  • (NullPromise) 


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# File 'lib/roby/promise.rb', line 350

def on_success(*)
    raise NullPromise, "attempting to add a step on a null promise"
end

#pending? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/roby/promise.rb', line 374

def pending?
    false
end

#reason ⇒ Object 



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# File 'lib/roby/promise.rb', line 400

def reason; end

#rejected? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/roby/promise.rb', line 386

def rejected?
    false
end

#state ⇒ Object 



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# File 'lib/roby/promise.rb', line 402

def state
    :fulfilled
end

#then ⇒ Object

Raises:

  • (NullPromise) 


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# File 'lib/roby/promise.rb', line 358

def then(*)
    raise NullPromise, "attempting to add a step on a null promise"
end

#unscheduled? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/roby/promise.rb', line 370

def unscheduled?
    false
end

#value ⇒ Object 



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# File 'lib/roby/promise.rb', line 392

def value(*)
    @value
end

#value! ⇒ Object 



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# File 'lib/roby/promise.rb', line 396

def value!(*)
    @value
end

#wait ⇒ Object 



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# File 'lib/roby/promise.rb', line 390

def wait; end