[x3d-public] x3d.py Re: Tree-to-tree transformation

[John Carlson]

It’s either program synthesis or use eval. I haven’t heard of alternatives.

John

On Wed, Aug 2, 2023 at 2:50 PM John Carlson <yottzumm at gmail.com> wrote:

> The JSON parser/loader is part of Python, so if you use it, fewer problems
> will happen, as you say.  There are VRML parsers/loaders in each VRML
> supporting browser.  I think X_ITE/x3d-tidy has one.  I’m just trying to
> get one loader working, and my current choice is python program synthesis.
> Ugh!  I guess i could write something that instantiates x3d instances with
> eval.  I’ve always heard that eval is a “bad thing,” but I’ve used it in a
> pinch.
>
> John
>
> On Wed, Aug 2, 2023 at 2:28 PM GPU Group <gpugroup at gmail.com> wrote:
>
>> I haven't seen any import functions in x3d.py. The code isn't too hard to
>> read. I think import is harder than export, because there are so many
>> things that can be wrong with an import file, and it's not 1:1. But
>> exporting --once you have a clean scenegraph-- is easy.
>> I think the default brute force way to import is to load a file into its
>> native tree -- html into an html tree, json into a json tree (like we load
>> glTF), x3d into an xml tree. There are standard loaders for those. Is there
>> a loader like that for vrml/classic/x3dv?
>> Then traverse that tree and convert to x3d.py nodes as you go.
>> -Doug
>> Here's another example code of a standalone program using x3d.py I was
>> working on recently.
>>
>> https://freewrl.sourceforge.io/tests/43_MIDI/88key/OLD/keyboard_gen_x3dpy.py
>>
>> - which shows a few more examples of the syntax x3d.py needs.
>> - program didn't work due to hard thing: a ProtoInstance with SFNode in
>> an MFNode fieldvalue. Hypotheses: H0: I'm not using the right syntax for
>> x3d.py in that case H1: x3d.py has a bug.
>> - But generally works pretty good once you figure out the syntax, class
>> names, fields etc.
>>
>>
>> On Wed, Aug 2, 2023 at 1:00 PM John Carlson <yottzumm at gmail.com> wrote:
>>
>>> I am thinking about X3d.py design.
>>>
>>> I was not aware if x3d.py had any input, clarification?
>>>
>>> I’m trying to read this:
>>>
>>> https://www.web3d.org/x3d/stylesheets/python/python.html
>>>
>>>
>>> It would seem appropriate to have a core X3D abstract python model, call
>>> it the python object model or POM, and then add what i call python “view,”
>>> “presentation,” or “encoding” models for XML, JSON, X3DOM, VRML, and X_ITE
>>> …input/output, perhaps generated by more than one stylesheet.  I think
>>> stuffing the encodings into one package is not the right design.  We should
>>> follow the standards way of separating abstract architecture from encoding
>>> and binding.
>>>
>>> I would propose stylesheets for each encoding,  just like we have for
>>> converting XML to various encodings, X3dTo….xslt.
>>>
>>> What’s the counter argument?
>>>
>>> I welcome any discussion, this is kind of the monolithic kernel versus
>>> microkernel idea i realize.  Monolithic won.
>>>
>>> This is also along the lines of HTMLElement, SVGElement, Node, and
>>> Element in ECMAScript.
>>>
>>> You can still stuff it all in the same x3d.py file, one can also support
>>> XML(), VRML() methods on the abstract model that defer or delegate to
>>> encoding models.  I don’t think anything breaks.
>>>
>>> Is this somehow un-pythonic?
>>>
>>> John
>>>
>>> On Wed, Aug 2, 2023 at 1:21 PM John Carlson <yottzumm at gmail.com> wrote:
>>>
>>>> Does anyone know good tools for tree-to-tree transformation?  I know
>>>> ANTLR and XML/XSL/XSLT.  I guess this is pretty much a compiler task.  Are
>>>> there tools for Classic VRML and JSON?  Python/Perl/ECMAScrpt?
>>>>
>>>> John
>>>>
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