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"L" == Laurent Duperval laurent.duperval@netergynet.com writes:

L> Hi, L> How do I do aggregation of objects? For example, in Java I have

L> class Foo { L> Class1 c1; L> Class2 c2; L> }

L> where Class1 and Class2 are two other classes. How do I create the same L> effect in XOTcl? I've tried a few variations but I don't get the effect I L> want so I guess I'm doing wrong.

Dear Laurent,

XOTcl supports dynamic aggregation of (a) objects and (b) classes. Your example resembles a static aggregation of objects (static, since you can't change the aggregation at runtime).

For object aggregation, one can do:

Class Class1 Class Class2

Class Foo Foo instproc init {} { Class1 [self]::c1 Class2 [self]::c2 }

Foo f

In order to change the aggregation, one can add new objects

Object f::o

The objects form an object tree, which can be disaggregated or moved etc. through the copy/move/destroy methods.

In addition to the aggregation of objects, XOTcl allows the aggregation of descriptive structures (classes) as well

Class C Class C::Foo

C::Foo instproc ... C::Foo proc ...

which supports the same methods for disaggregation etc. like for object aggregation.

For a more detailed discussion about aggregation in XOTcl see: http://nm.wu-wien.ac.at/research/publications/sac.pdf

L> Also, how do you create and use private data? By this I mean data (and L> possibly methods) which are only accessible by the class or the object.

XOTcl has no native support for private data. The idea of private data conflicts to a certain point with the idea of introspection and reflection. However, one can achieve a similar behavior through refinement of the set method (and by deactivating the Tcl set command). For the refinement you can define for example a set method on the class level, mixins or filters.

hope this helps best regards

-gustaf neumann