Class: Libuv::Q::Deferred

Inherits:
Object
  • Object
show all
Includes:
Libuv::Q
Defined in:
lib/libuv/q.rb

Overview

The purpose of the deferred object is to expose the associated Promise instance as well as APIs that can be used for signalling the successful or unsuccessful completion of a task.

Instance Method Summary collapse

Methods included from Libuv::Q

all, any, defer, finally, reject

Constructor Details

#initialize(loop) ⇒ Deferred

Returns a new instance of Deferred.



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# File 'lib/libuv/q.rb', line 202

def initialize(loop)
	super()
	
	@pending = []
	@value = nil
	@loop = loop
end

Instance Method Details

#notify(*args) ⇒ Object

Provides an asynchronous callback mechanism

Parameters:

  • data (*Object) —

    you would like to send down the promise chain.



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# File 'lib/libuv/q.rb', line 251

def notify(*args)
	@loop.schedule do 	# just in case we are on a different event loop
		if @pending && @pending.length > 0
			callbacks = @pending
			@loop.next_tick do
				callbacks.each do |callback|
					callback[2].call(*args)
				end
			end
		end
	end
end

#promise ⇒ Object

Creates a promise object associated with this deferred



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# File 'lib/libuv/q.rb', line 243

def promise
	DeferredPromise.new(@loop, self)
end

#reject(reason = nil) ⇒ Object

rejects the derived promise with the reason. This is equivalent to resolving it with a rejection constructed via Q.reject.

Parameters:

  • reason (Object) (defaults to: nil) —

    constant, message, exception or an object representing the rejection reason.



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# File 'lib/libuv/q.rb', line 236

def reject(reason = nil)
	resolve(Q.reject(@loop, reason))
end

#resolve(val = nil) ⇒ Object

resolves the derived promise with the value. If the value is a rejection constructed via Q.reject, the promise will be rejected instead.

Parameters:

  • val (Object) (defaults to: nil) —

    constant, message or an object representing the result.



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# File 'lib/libuv/q.rb', line 215

def resolve(val = nil)
	@loop.schedule do
		if not @pending.nil?
			callbacks = @pending
			@pending = nil
			@value = ref(@loop, val)
			
			if callbacks.length > 0
				callbacks.each do |callback|
					@value.then(callback[0], callback[1], callback[2])
				end
			end
		end
	end
end