Ambient-Oriented Programming

User Tools

Site Tools

Trace:
at:tutorial:actors

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revisionPrevious revision
Next revisionBoth sides next revision
at:tutorial:actors [2007/07/18 11:11] – elisagat:tutorial:actors [2007/07/18 11:21] – elisag
Line 204: Line 204:
  
 The solution proposed in the [[http://www.erights.org|E language]], and adopted in AmbientTalk, is to disallow direct access to a future by any object. Instead, objects may **only** send **asynchronous** messages to a future object. This enables the future to temporarily buffer such messages until its resolved value is known. The net effect of this solution is that futures actually can be "chained", forming asynchronous //pipelines// of messages, as will be further explained in the next section. The solution proposed in the [[http://www.erights.org|E language]], and adopted in AmbientTalk, is to disallow direct access to a future by any object. Instead, objects may **only** send **asynchronous** messages to a future object. This enables the future to temporarily buffer such messages until its resolved value is known. The net effect of this solution is that futures actually can be "chained", forming asynchronous //pipelines// of messages, as will be further explained in the next section.
 +
 +==== Working with Resolved Futures ====
  
 When a future eventually becomes resolved with a value, any messages that were accumulated by the future are forwarded asynchronously to the actual return value, such that it appears as if the original object had sent the messages to the actual return value in the first place. When a future eventually becomes resolved with a value, any messages that were accumulated by the future are forwarded asynchronously to the actual return value, such that it appears as if the original object had sent the messages to the actual return value in the first place.
Line 210: Line 212:
 AmbientTalk only allows one method to be synchronously invoked on a future, the ''=='' method. A word of warning though: equality on futures is defined as pointer equality, so a future will only be equal to itself. It does not compare the parameter object with its actual value, if it would be resolved. AmbientTalk only allows one method to be synchronously invoked on a future, the ''=='' method. A word of warning though: equality on futures is defined as pointer equality, so a future will only be equal to itself. It does not compare the parameter object with its actual value, if it would be resolved.
 </note> </note>
- 
-==== Working with Resolved Futures ==== 
  
 As explained above, it is always correct to use asynchronous message sends to communicate with a future. Sometimes, however, we may want to perform some operation on the return value other than message sending, for example, printing it to the screen. If you print the future directly, you get the following: As explained above, it is always correct to use asynchronous message sends to communicate with a future. Sometimes, however, we may want to perform some operation on the return value other than message sending, for example, printing it to the screen. If you print the future directly, you get the following:
Line 271: Line 271:
 </code> </code>
  
-Finally, it is useful to know that ''when:becomes:'' itself returns a future, who will be resolved with the value of applying the observer closure:+Finally, it is useful to know that ''when:becomes:'' itself returns a future, who will be resolved with the value of applying the observer closure: 
  
 <code> <code>
Line 279: Line 279:
 </code> </code>
  
-When the future for ''<-add(1,2)'' becomes resolved with ''sum'', the ''fut'' future will be resolved with the future for the ''<-add(sum,3)'' message. When that message finally returns yet another sum, that sum will become the value of ''fut''.+When the future for ''<-add(1,2)'' becomes resolved with ''sum'', the ''fut'' future will be resolved with the future for the ''<-add(sum,3)'' message. When that message finally returns yet another sum, that sum will become the value of ''fut''. This example also illustrates how futures can be chained by means of the ''when:becomes:'' function forming the so-called asynchrounous pipelines of messages. 
  
 ==== Futures and Annotated Messages ==== ==== Futures and Annotated Messages ====
at/tutorial/actors.txt · Last modified: 2020/02/05 21:26 by elisag