[x3d-public] IMPORT/EXPORT Use [was: Statement permitted placements]

[Leonard Daly]

Roy did a very detailed analysis of statement location.

I think that any discussion of IMPORT / EXPORT statements may be 
premature until it is figured out how files and their nodes will be 
inlined in HTML. There is a single namespace and namescope in HTML 
causing the following issues when X3D is integrated with DOM:

1) All nodes are available to all other nodes at all times
2) IMPORT does not have any meaning
3) EXPORT does not have any meaning
4) Uncertain how to handle a file that gets Inlined more than once since 
all DEF and ID from the Inline will be duplicated

Possible solutions are:
A) Do not put the contents of any Inline into the DOM
B) Do not put the contents of any X3D file into the DOM
C) Modify the DEF & ID values on each Inline so they are unique

(A) has the potential problem of completely hiding all of the interior 
nodes and making it unavailable. In this case IMPORT and EXPORT can be 
defined to make sense by providing access to those fields. Unfortunately 
this breaks a different goal of full DOM integration.

(B) This is like (1), but more extreme. It essentially makes X3D 
plugin-like in that there is complete separation between DOM and X3D.

There is a variant on (A)/(B) where only certain (developer 
controllable) Inline contents are loaded into the DOM. This partially 
breaks the goal of DOM integration and still leaves the problem of 
keeping DEF/ID values unique (C)

(C) This solution creates a virtual namescope in that the DEF/ID values 
are modified so that they are unique within the parent DOM. This is 
potentially tricky since these values can be programmatically assembled. 
It might be possible to make all of the necessary modifications to the 
nodes in the Inline file, but unsolvable (or close to it) to change 
other code in either the parent or other Inline nodes that may 
cross-refer to those values.


-- 
*Leonard Daly*
3D Systems & Cloud Consultant
LA ACM SIGGRAPH Chair
President, Daly Realism - /Creating the Future/
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