Ambient-Oriented Programming

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at:tutorial:modular [2008/09/17 17:13]
tvcutsem added 		at:tutorial:modular [2013/02/26 15:52]
cfscholl
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 Whenever a new actor is created by the AmbientTalk interpreter, it uses the entries in the object path to initialize the ''lobby'' object of the actor. Hence, by starting up the interpreter as shown above, executing ''lobby.lib'' in any actor returns a reference to a namespace object bound to the ''examples'' directory. This effectively removes absolute path names from AmbientTalk source code and even enables you to quickly reconfigure AmbientTalk code to use other libraries by loading the code using another object path. Whenever a new actor is created by the AmbientTalk interpreter, it uses the entries in the object path to initialize the ''lobby'' object of the actor. Hence, by starting up the interpreter as shown above, executing ''lobby.lib'' in any actor returns a reference to a namespace object bound to the ''examples'' directory. This effectively removes absolute path names from AmbientTalk source code and even enables you to quickly reconfigure AmbientTalk code to use other libraries by loading the code using another object path.
 +
 +Think of AmbientTalk's object path as the equivalent of Java's classpath.
  
 <note> <note>
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 <code> <code>
 def Enumerable := object: { def Enumerable := object: {
-  def collect: clo { /* as before */ } +  def collect: clo { /* as before */ }; 
-  def detect: pred { /* as before */ } +  def detect: pred { /* as before */ }; 
-  def reject: pred { /* as before */ }+  def reject: pred { /* as before */ };
   def each: clo @Required;   def each: clo @Required;
 } }
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 Type tags can best be compared to empty Java interface types. Such empty interfaces are sometimes used in Java purely for the purposes of marking an object. Examples are ''java.io.Serializable'' and ''java.lang.Cloneable''. An empty interface type can be implemented by any class (object) and hence only serves the purpose of distinguishing objects by type (by means of ''instanceof'' in Java). Type tags can best be compared to empty Java interface types. Such empty interfaces are sometimes used in Java purely for the purposes of marking an object. Examples are ''java.io.Serializable'' and ''java.lang.Cloneable''. An empty interface type can be implemented by any class (object) and hence only serves the purpose of distinguishing objects by type (by means of ''instanceof'' in Java).
 </note> </note>
 +
  
 ==== Native Type Tags ==== ==== Native Type Tags ====
  
-The module ''/.at.types'' shipped with the system library contains the type definitions of the native data types of the interpreter. These type tags can be used to perform type tests on objects, for example:+The module ''/.at.lang.types'' shipped with the system library contains the type definitions of the native data types of the interpreter. These type tags can be used to perform type tests on objects, for example:
  
 <code> <code>
-is: 1 taggedAs: /.at.types.Number+is: 1 taggedAs: /.at.lang.types.Number
 >> true >> true
-is: "foo" taggedAs: /.at.types.Text+is: "foo" taggedAs: /.at.lang.types.Text
 >> true >> true
 </code> </code>
  
-The type ''/.at.types.Isolate'' can be used to mark an object as an isolate. Isolate objects are similar to serializable Java objects. They are explained when introducing concurrent programming in [[at:tutorial:actors|a later chapter]].+The type ''/.at.lang.types.Isolate'' can be used to mark an object as an isolate. Isolate objects are similar to serializable Java objects. They are explained when introducing concurrent programming in [[at:tutorial:actors|a later chapter]].
  
 ==== Type tags as annotated message sends ==== ==== Type tags as annotated message sends ====
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 In the [[at:tutorial:actors|chapter on actors]] we use this feature to distinguish purely asynchronous message sends from so-called //future-type// message sends. If the message send is annotated with the ''FutureMessage'' type tag, the asynchronous send returns a future, otherwise it returns ''nil''. In the [[at:tutorial:actors|chapter on actors]] we use this feature to distinguish purely asynchronous message sends from so-called //future-type// message sends. If the message send is annotated with the ''FutureMessage'' type tag, the asynchronous send returns a future, otherwise it returns ''nil''.
 +
  
 ===== Exception Handling ===== ===== Exception Handling =====
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 </code> </code>
  
-Note that a new instance of an object named ''XDivisionByZero'' is raised, not the type tag ''DivisionByZero'' itself. An exception is any object that is tagged with (a subtype of) the ''lobby.at.types.Exception'' type tag. By convention, an exception should have the fields ''message'' and ''stackTrace''. The exception module found under ''lobby.at.exceptions'' contains an auxiliary function named ''createException'' which takes a type tag as argument and returns a new prototype exception object. For example:+Note that a new instance of an object named ''XDivisionByZero'' is raised, not the type tag ''DivisionByZero'' itself. An exception is any object that is tagged with (a subtype of) the ''lobby.at.lang.types.Exception'' type tag. By convention, an exception should have the fields ''message'' and ''stackTrace''. The exception module found under ''lobby.at.lang.exceptions'' contains an auxiliary function named ''createException'' which takes a type tag as argument and returns a new prototype exception object. For example:
  
 <code> <code>
-deftype DivisionByZero <: lobby.at.types.Exception; +deftype DivisionByZero <: lobby.at.lang.types.Exception; 
-def XDivisionByZero := lobby.at.exceptions.createException(DivisionByZero);+def XDivisionByZero := lobby.at.lang.exceptions.createException(DivisionByZero);
 </code> </code>
  
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     system.println(exc.message);     system.println(exc.message);
   };   };
-})+} taggedAs: [/.at.lang.types.Handler])
 </code> </code>
  
at/tutorial/modular.txt · Last modified: 2013/05/17 20:24 by tvcutsem

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