Re: Lua as a "domain specific language"?

[Thomas Wrensch <twrensch@...>]

On Wed, 22 Mar 2006, PA wrote:

> On Mar 10, 2006, at 01:19, Thomas Wrensch wrote:
>
> > I've also used Lua to build a very-high level modeling language for 
> > object-oriented systems. This was a more traditional DSL for designers of 
> > object-oriented software systems. Rather than using Lua's syntax directly 
> > it implements a language parser in Lua.
>
> I was wondering if you could provide some example of your modeling language?
>
> How does it compare, relate to something like UML Object Constraint Language 
> (OCL)?


The language is a research prototype, and not ready for prime time. Here's 
a quick overview for anyone else who is interested. Since this is 
off-topic I'll send a more detailed description directly.



The idea is to build a model of a set of classes that can be interpreted 
to create the classes themselves. For example, the following would build 
simple BookTitle and Book classes with appropriate interaction between 
them (this is the boring part, but is necessary background):

    class(BookTitle)
    class(Book)
    value(Book.title, BookTitle)
    value(BookTitle.author, String)
    -- etc. as needed

The above is not much better than writing code in a decent OO language. 
The value comes from the ability to define patterns of interaction. For 
example, if BookTitle and Book cooperated to maintain a list in BookTitle 
of all the Books that were of that type. (BookTitle contains a list of 
Books):

    manytoone(BookTitle.books, Book.title)

This declaration builds all the model elements necessary to make this 
pattern work. Note that manytoone is not built in to the system, rather it 
is defined by the user of the system or included in a library of such 
definitions. Thus it has much of the power of RoR, but is easily 
extensible.

And of course, all my research prototypes for this work (there are three 
that test out different ideas) are written in Lua  :-).

  - Tom