Differences

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

--- at:tutorial:appendix [2008/07/10 16:31] – added tvcutsem
+++ at:tutorial:appendix [2008/07/10 16:46] – * tvcutsem
@@ Line 1: / Line 1: @@
-====== Appendix ======
+====== Appendix: Libraries ======
 In the appendix, we explain useful libraries available to the AmbientTalk/2 programmer. These libraries provide abstractions ranging from traditional, established "collections" up to newly researched language constructs, such as "ambient references".
@@ Line 536: / Line 536: @@
 You can also force a ''StructuralTypeMismatch'' exception to be raised if the object does not conform to the type:
- *  ''ensure: tom implements: PersonProtocol'' => true or exception
+  *  ''ensure: tom implements: PersonProtocol'' => true or exception
- *  ''PersonProtocol.checkConformance(tom)'' => true or exception
+  *  ''PersonProtocol.checkConformance(tom)'' => true or exception
 More usage examples of structural types can be found in the unit test defined in the file ''at/lang/structuraltypes.at''.
 ==== Traits ====
+The module ''/.at.lang.traits'' exports a small library to use AmbientTalk's traits in a more structured manner. In the literature, traits are described as reusable components with two interfaces: an interface of methods that are //provided// by the trait //to// the composite and an interface of methods that are //required// by the trait //from// the composite. AmbientTalk's traits only make the provided interface explicit. The required interface remains implicit and unchecked at composition time.
+Using the ''traits'' module, a trait can specify that it requires its composite to adhere to a certain protocol (i.e. a structural type, cf. the previous section). Using traits in this way requires an explicit composition step where the trait's requirements are checked.
+To define a "structured" trait, define your  trait objects as follows:
+<code>
+trait: {
+  ...
+} requiring: Protocol;
+</code>
+The above code creates a trait that can only be composed into an object adhering to the specified protocol. To compose traits, use the following language construct:
+<code>
+object: {
+  use: {
+    import T1 exclude ...;
+    import T2 alias ...;
+  }
+}
+</code>
+The ''use:'' block can **only** include ''import'' statements. It simply executes the ''import'' statements, but in addition checks whether the composite, //after// having imported all of its traits, provides all of the methods specified in the required protocol of its imported traits.
+Note that the place where ''use:'' is used inside an object matters: if one of the traits requires a method ''m()'' that is defined only later in the composite, the check will fail. To avoid this, place the ''use:'' block at the bottom of the object declaration.
+Usage examples can be found in the unit tests in the file ''at/lang/traits.at''.
+===== Utilities =====
+The files in the ''at/support'' subdirectory of the standard library implement various utilities of use to the AmbientTalk programmer. We discuss the most useful modules below.
+==== Timing Utilities ====
+==== Logging Framework ====
+==== Object Inspector ====
+==== Symbiosis Utilities ====
+==== Miscellaneous ====