Prototype OO was Re: Inheritance/defaulting of attributes

dak at sq.com dak at sq.com
Fri Oct 17 19:25:14 BST 1997


[Lee mentioned (Hi, Lee!), in passing comment about the 
Model-View-Controller paradigm]:

| SoftQuad's Sculptor SGML product used (uses, if they still sell it) an MVC
| paradigm, together with an object-oriented dialect of Scheme. Today one
| would probably use Java rather than Scheme because more programmers would
| like it, although Scheme goes well with DSSSL.  But once you'd got
| over the rather steep learning curve, Sculptor is/was pretty powerful.

We're still selling it, I'm happy to say.

One minor point of clarification (not to distract from this very interesting
conversation about OO models!):

[...]

| SoftQuad Sculptor doesn't give much access to the DTD.

Hmm.  I think I'd put that another way:  Sculptor's access to the DTD
is abstracted for editing, at the level of:

1)  You can get access to the definitions of atomic items in the DTD
(elements, attributes, general entities, parameter entities, notation 
entities), and

2)  You can get access to some of the relations between these
(e.g. for elements: element-content-type, attribute-definition-list) but

3)  Access to the content model is:

3.1) by type, if you ask the document or DTD:
  ANY, EMPTY, CDATA, RCDATA, MIXED, ELEMENT, or CONREF, and

3.2) by the various DTD constraints on how the document manipulation 
primitives act, which can also be pre-tested, by (e.g.) can-insert?.

...which is when it's needed in the editing environment.  Sometimes,
it would be nice to have more, but you can generally synthesize what
you need, which is a large part of the advantage of having a general-
purpose, dynamic programming language in the scripting environment.

[End of digression.  Back to the regularly scheduled abstract discussion
about OO in the markup environment.]

Best,
Dak

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