Raloo classes are Tcloo classes with object data stored in a TclRAL relvar. "A match made in heaven, or a marriage made in hell? You decide at the end of the talk" Raloo objects refernce tuples in the class relvar. The relationships are TclRAL relvar constraints. Referential integrity is checked automatically at appropriate time for the entire class model, without you having to write any code. Raloo supports associating a state machine with a class for async processing. Processing is accompanied by writing ordinary Tcl code.
Three projections of a Raloo solution:
In Tk event loop is already running; in tclsh Raloo programs have the flavor of a Tk application.
One Button Microwave
[Showed a graphical representation of the above.] All ovens have a lamp and a tube. No tubes or lamps exist without an oven. Showed example code implementing an Oven class. Code to define attributes, relationships, Code to run at lifecycle transitions. This example (documentation, code) in the Tcl Raloo package.
Question from the chat: can you have null attributes? Answer: Not really since Tcl does not have a concept of null, but if there ever were a change so that there was a "null" Tcl_Obj and expr were modified to support three-value logic, then everything should just work.
[Ran the one-button microwave demo]
The ideas behind Raloo are not new or original. Three projections of the problem space: static structure encoded as a relation class model; dynamics encoded as a state machine; algorithms written in code; capture program structure declaratively. Raloo execution semantics match those of Executable UML ("not your grandmother's UML"). Raloo combines the foundations provided by TclRAL (a complete relational algebra) and TclOO (set of object oriented building blocks).
Download from http://sourceforge.net/projects/tclral
Requires TclOO (0.5.1), Tcl 8.5 (or better presumably; hasn't personally had time to try with alpha versions of 8.6 yet). "Read the paper! Please." More examples, explanation and references there.
Q: How many microwaves can you run? A: I only have room for 12-15 on my screen at a time (Linux on celeron) Q: Limits on the # of rows? A: Just a function of memory. Has a colleague who has serialized 95 megs worth of TclRAL relations.