Yes, just yesterday we discussed about it and in what direction we want to push our models. We also discussed about maybe merging Magritte and Meta. I also learned that he is going into the direction of automatic code-generation, something that I always wanted to avoid ... Lukas -- Lukas Renggli http://www.lukas-renggli.ch

What's Meta, this is the first I've heard of it? Ramon Leon http://onsmalltalk.com

In fact the story is like that Moose without description in 1996 -> slowly got a ER metametamodel -> slowly got a MOF meta meta model (no relations or badly done I did it :)) -> I work with frederick to put a meta model in SmallWiki -> lukas saw got it right meta described magritte with itself and we got Magritte -> Adrian kuhn got some fun reading the EMOF 2.0 spec and reimplemented totally the bad Moose metamodel. It is cool to work with smart guys that take ideas and transcend them, really. Now we are looking at them and checking how we can learn. Magritte is more data oriented and Moose Meta is more a traditional object-oriented metametamodel. But this is interesting to get exposed. On 16 janv. 07, at 17:22, Lukas Renggli wrote:

We are talking - I think the ball is in my court to get the glorp port upgraded so it is in sync with the current version. Then I'l integrate my stuff that generates alter scripts. Ramon is working on mapping the model and has a start on it. I have to look into his work. I'm a little strapped for time just now but it will come soon. -Todd Blanchard On Jan 13, 2007, at 3:05 PM, J J wrote:

FWIW, I think the port is about 80% done - I hope to wrap it up by beginning of next week if all goes well. Also, I have take over ownership of the glorp entry on squeakmap. -Todd On Jan 15, 2007, at 5:14 PM, Ramon Leon wrote:

That depends on where the recursion happens. Imagine the following problem: Person class>>descriptionPartner ^ MAToOneRelationDescription new reference: self description; yourself This is purely Smalltalk and Magritte cannot do anything about the recursion caused here. When you evaluate "Person description" Magritte will collect all the description elements and also call #descriptionPartner that calls #description and leads to an infinite recursion. 1. The simplest solution to this problem is a hack: Person class>>descriptionPartner ^ (MAToOneRelationDescription selector: #partner) reference: (MADynamicObject on: [ self description ]); yourself MADynamicObject is a proxy that delegates most of its messages to the result of the block evaluation. This is easy and mostly works, however it is very hard to debug and usually leads to problems sooner or later. There are a couple of examples in Magritte, Pier and Pier- Unix-Security of this hack. This does not solve the problem with the recursion when validating or printing the object. 2. Another solution is just to exclude the circular references from the referenced: Person class>>descriptionPartner ^ (MAToOneRelationDescription selector: #partner) reference: (MADynamicObject on: [ self descriptionWithoutReferences ]); yourself And then you need to implement something like this: Object class>>descriptionWithoutReferences ^ self description reject: [ :each | each isKindOf: MAReferenceDescription ] Not very nice, but it works well. It should also solve the problem when validating or printing a recursive object. 3. Compose your descriptions dynamically on the instance side. Person>>description | desc part | desc := MAContainer new. part := MAToOneRelationDescription selector: #partner. desc add: (part copy reference: part). ^ desc Ugly and looks like a Java UI built manually, but it also works for validating or printing recursive objects. As I mentioned in earlier mails the goal would be to enable the detection of recursion in validation, printing and serialization automatically. Note: Magritte seems to lack some feature in the field of complex composed objects (especially if you compare it with EMOF that has something like an 'opposite' for back references, etc). This comes from the fact that most (or even all) my described objects form a tree and not a graph with loops. Of course the object model has loops, but they are all handled manually with the glue-code in- between that is not considered by Magritte. That's the power of Smalltalk, everything is real close together ... HTH, Lukas -- Lukas Renggli http://www.lukas-renggli.ch