[dfdl-wg] Notes from Telecon 2005-11-23

[Mike Beckerle]

Notes from DFDL call 2005-11-23 by Mike Beckerle


Review of trackers

Arrays - waiting on extensibility

Scoping - not blocked. Design team discussions underway. Shooting for 
design-team resolution in 7 to 14 days then to WG.

Layers - waiting on (or part of?) extensibility

Null & Default - not blocked. Internal design-team discussions/drafts 
ongoing.

Property List - not blocked. Suman has done some work recently. Dependent 
on organization of properties which depends on scoping.

Open Content & Wildcards - not blocked. Distributed discussion doc to WG.

Choice and Guards - not blocked. Distributed discussion doc to WG. 

Use Statement - unblocked. Low priority. (note taker's revision - this is 
actually pending the scoping stuff, not just because I'm working on both, 
but it is tied up there technically also.)

Extensibility - not blocked. Conf. call held. Need to write up ideas from 
it. Several trackers depend on this one. Document in formulation by design 
team members.

Expressions - waiting on scoping. Should study XSL variables in 
expressions.

Parameters and Keying - doc distributed to WG. Make Priority 2? Other 
items depend on this. Interacts with choice and guards.

Late Binding - internal discussions in team. Related to parameters and 
keying.

Parser behavior - place holder for topics we didn't want to drop. Move 
ownership from Bob McGrath to Steve Hanson and/or Geoff Judd?

Packed bits - place holder to remind us we need to revisit this topic. Low 
prio for now.

Pointers - place holder. MikeB suggested pointers might not be important 
for v1.0 of DFDL? Jim Myers indicated there needs to be some way to do 
them. I.e., someone with a format that has pointers in it still needs to 
be able to use DFDL even if it doesn't help them with the pointer aspect. 

Paramters and Keying discussion 

We'll continue discussion on next week's call. 

Jim Myers(JM) - overlaps with extensibility. Looks alot like white-box 
transforms.

Steve Hanson(SH) - yes, that was also observed though we didn't write it 
up.

JM - are there examples that can't or shouldn't be thought of as 
transforms?

Bob McGrath (BM) - can variables hold the value of another variable? Lots 
of papers on language design. Is this proposal a sensible one?

JM - can variables be reset? Can we make sure we know how to order and 
parse things? I.e., do we need rules like defining variables "above" their 
point of use?

Geoff Judd (GJ) - Agrees that we need such rules.

BM - relationship to XSL variables? Similarities/differences. Finds XSL 
variables and their rules complex.

GJ - comment on XSL (didn't catch this in my notes)

Martin Westhead (MW) - XSL variables are single assignment.

SH - need default value in addition to "override" or setting.

JM - we have defaults for data items. Can we use that mechanism and avoid 
another defaults-resolution means for parameters/variables?

Mike Beckerle (MB) - in declarative languages, variables with assignment 
can be problematic because the order of execution isn't so clear. The 
reason to use a declarative language is to allow the implementation to 
reorder things and so forth. Makes free assignment of variables an issue, 
so single assignment makes sense.

End Notes
Mike Beckerle
STSM, Architect, Scalable Computing
IBM Software Group
Information Integration Solutions
Westborough, MA 01581
voice and FAX 508-599-7148
home/mobile office 508-915-4767
skype ID mbeckerle
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