Class: Lazy::Promise

Inherits:

Object

• Object
• Lazy::Promise

show all

Defined in:

lib/core/facets/lazy.rb

Overview

Constant Summary

DIVERGES =

diverges

Instance Method Summary (collapse)

• - (Object) __result__

  :nodoc:.

• - (Object) __synchronize__

  :nodoc:.

• - (Promise) initialize(&computation) constructor

  :nodoc:.

• - (Object) inspect

  :nodoc:.

• - (Object) method_missing(*args, &block)

  :nodoc:.

• - (Boolean) respond_to?(message)

  :nodoc:.

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# File 'lib/core/facets/lazy.rb', line 69

def initialize( &computation ) #:nodoc:
  @computation = computation
end

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# File 'lib/core/facets/lazy.rb', line 125

def method_missing( *args, &block ) #:nodoc:
  __result__.__send__( *args, &block )
end

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# File 'lib/core/facets/lazy.rb', line 84

def __result__ #:nodoc:
  __synchronize__ do
    if @computation
      raise LazyException.new( @exception ) if @exception

      computation = @computation
      @computation = DIVERGES # trap divergence due to over-eager recursion

      begin
        @result = demand( computation.call( self ) )
        @computation = nil
      rescue DivergenceError
        raise
      rescue Exception => exception
        # handle exceptions
        @exception = exception
        raise LazyException.new( @exception )
      end
    end

    @result
  end
end

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# File 'lib/core/facets/lazy.rb', line 72

def __synchronize__ #:nodoc:
  yield
end

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# File 'lib/core/facets/lazy.rb', line 108

def inspect #:nodoc:
  __synchronize__ do
    if @computation
      "#<#{ __class__ } computation=#{ @computation.inspect }>"
    else
      @result.inspect
    end
  end
end

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# File 'lib/core/facets/lazy.rb', line 118

def respond_to?( message ) #:nodoc:
  message = message.to_sym
  message == :__result__ or
  message == :inspect or
  __result__.respond_to? message
end